WfrU' 

University  of  California  •  Berkeley 


Bulletin  No.  254 


o   •    f  A,  Economic  Geology,  49 
Senes  U  Descriptive  Geology,  61 


DEPARTMENT  OF  THE  INTERIOR 
UNITED  STATES  GEOLOGICAL  SURVEY 

CHARLES  D.  WALCOTT,  DIRECTOR 


REPORT  OF  PROGRESS 


IN   THE 


GEOLOGICAL  RESURYEY  OF  THE  CRIPPLE 
CREEK  DISTRICT,  COLORADO 


WALDEMAR  LINDGREN  AND  FREDERICK  LESLIE  RANSOME 


WASHINGTON 

GOVERNMENT    PRINTING    OFFICE 
1904 


Bulletin  No.  254 


a..  .  /  A,  Economic  Geology,  49 
es\B,  Descriptive  Geology,  61 


DEPARTMENT  OF  THE  INTERIOR 

UNITED  STATES  GEOLOGICAL  SURVEY 

CHARLES  D.  WALCOTT,  DIRECTOR 


REPORT  OF  PROGREi 


IN  THE 


GEOLOGICAL  RESURVEY  OF  THE  CRIPPLE 
CREEK  DISTRICT,  COLORADO 


BY 


WALDEMAR  LINDGREN  AND  FREDERICK  LESLIE  RANSOME 

v\ 


WASHINGTON 

GOVERNMENT     PRINTING     OFFICE 

1904: 


i!i   RANOROI  i  i  (HRARY 


CONTENTS. 


Page. 

3tter  of  transmittal 5 

Introduction 7 

Production 8 

Mining  and  metallurgy 9 

Topography 11 

General  geology , 11 

First  geological  survey  of  the  district 11 

Modifications  of  earlier  results 12 

Economic  geology 14 

Earlier  work 14 

Extent  of  productive  territory 14 

Underground  development 15 

Brief  review  of  the  mines 15 

Character  of  the  ores 20 

Structural  characteristics  of  the  deposits 22 

Types  of  deposits 22 

Depth  of  oxidized  zone 26 

Relations  of  ore  bodies  to  depth 26 

Underground  water -_ 31 

Subterranean  gases 32 

Future  of  the  district 33 

Index  . .  35 


LETTER  OF  TRANSMITTAL. 


DEPARTMENT  OF  THE  INTERIOR, 
UNITED  STATES  GEOLOGICAL  SURVEY, 

Washington,  D.  (7.,  Novembers,  1904. 
SIR:  I  have  the  honor  to  transmit  herewith  the  manuscript  of  a  pre- 
liminary report  on  a  "Resurvey  of  the  Cripple  Creek  district  of  Colo- 
rado," by  Messrs.  Waldemar  Lindgren  and  F.  L.  Ransoine,  under  my 
general  supervision. 

Although  only  ten  years  had  elapsed  since  a  careful  study  of  the 
geology  of  this  district  was  made  by  Messrs.  Cross  and  Penrose,  the 
people  of  Colorado  had  been  so  strongly  impressed  with  the  economic 
importance  of  a  scientific  examination  of  the  ground  opened  by  mining 
operations  during  that  period,  that  they  urgently  requested  this  resur- 
vey  and  have  materially  assisted  in  its  execution. 

The  present  report,  made  in  advance  of  the  final  laboratory  exami- 
nations, is  a  summary  of  those  facts  that  bear  upon  the  economic 
development  of  the  region  and  are  of  immediate  importance  to  the 
miners.  I  therefore  request  that  it  be  published  with  the  least  possi- 
ble dela}^r  that  its  results  may  be  promptly  available  to  all  interested 
in  the  region. 

Very  respectfully, 

S.  F.  EMMONS, 

Geologist  in  Charge  Section  of  Metalliferous  Deposits. 
Hon.  CHARLES  D.  WALCOTT, 

Director  United  States  Geological  Survey. 


REPORT  OF  PROGRESS  IN  THE  GEOLOGICAL  RESURVEY 
OF  THE  CRIPPLE  CREEK  DISTRICT,  COLORADO. 


By  WALDEMAR  LINDGREN  and  FREDERICK  LESLIE  RANSOME. 


IKTRODTTCTIOX. 

The  Cripple  Creek  gold  deposits  were  discovered  in  1891.  Shortly 
afterwards,  in  1894,  an  examination  of  the  new  district  was  undertaken 
by  the  United  States  Geological  Survey,  Mr.  Whitman  Cross  having 
charge  of  geology  and  petrography  and  Mr.  R.  A.  F.  Penrose,  jr., 
undertaking  the  examination  of  the  mines.  Their  report,  accompanied 
by  a  geological  map,  was  published  in  the  Sixteenth  Annual  Report  of 
the  Geological  Survey,  Part  II,  pages  1-207,  and  has  for  the  last  ten 
years  served  as  a  useful  and  accurate  geological  guide  to  mining 
operations. 

With  the  astonishingly  rapid  development  of  the  Cripple  Creek 
mines  the  opportunities  for  geological  study  multiplied,  revealing 
great  complexity  of  vein  phenomena  and  stimulating  a  desire  for  fur- 
ther investigation,  particularly  with  a  view  of  obtaining  some  evidence 
as  to  the  persistence  of  the  veins  in  depth.  This  desire  found  expres- 
sion in  a  request  by  citizens  of  Colorado  for  a  reexamination  of  the 
district  by  the  United  States  Geological  Survey  and  in  an  offer  of 
cooperation,  whereby  the  cost  would  be  equally  divided  between  the 
State  of  Colorado  and  the  National  Survey.  The  necessary  amount 
having  been  subscribed  in  Cripple  Creek,  Colorado  Springs,  and  Den- 
ver, the  State  contribution  was  put  in  the  hands  of  Mr.  John  Welling- 
ton Finch,  State  geologist  of  Colorado,  and  by  him  disbursed.  The 
cordial  thanks  of  the  geologists  in  charge  of  the  work  are  due  to  Mr. 
Finch  for  his  hearty  and  efficient  cooperation. 

The  reexamination  began  with  a  thorough  revision  of  the  topographic 
map  of  Cripple  Creek  by  Mr.  R.  T.  Evans,  Mr.  E.  M.  Douglas  in 
charge.  This  involved  a  great  deal  of  painstaking  work,  nearly  every 
prospect  hole  being  located,  as  well  as  all  shafts  and  tunnels.  The 
new  map  is  on  the  scale  of  1:19,495,  or  about  2i  inches  to  the  mile, 
and  includes  practically  the  same  area  as  the  old  map,  a  small  strip 
only  being  added  on  the  western  side,  so  that  the  total  area  mapped  is 
about  40  square  miles.  The  small  developments  outside  of  this  area 

'  7 


RESURVEY    OF    CEIPPLE    CKEEK    DISTRICT.  [BULL.  254. 

did  not  seem  to  justify  further  extension  of  the  boundaries.  Contours 
are  50  feet  apart,  and  a  numbered  list  of  324  mines  is  given  on  the 
margin  of  the  sheet.  A  line  of  accurate  levels  was  run  to  Cripple 
Cr6ek  from  Colorado  Springs,  thus  settling  the  conflicting  data  of  the 
different  railroads. 

The  geological  and  mining  work  was  undertaken  jointly  by  the 
authors  of  this  preliminary  report.  The  examination  began  in  June, 
1903,  and,  with  some  interruptions,  due  to  various  causes,  the  field 
work  was  concluded  in  April,  1904.  Practically  every  accessible  mine 
in  the  district  was  examined  in  greater  or  less  detail.  Mr.  L.  C.  Gra- 
ton  served  as  assistant  throughout  this  time,  actively  participating  in 
all  branches  of  the  work.  Messrs.  A.  M.  Rock  and  J.  Bruce  also 
rendered  very  efficient  aid  as  draftsmen. 

PBODTJCTIOK. 

Though  situated  close  to  the  centers  of  population  in  Colorado  and 
in  an  easily  accessible  region,  the  gold  deposits  of  Cripple  Creek  were 
not  discovered  until  1891.  To  a  great  extent  the  lateness  of  the  dis- 
covery was  due  to  the  extremely  inconspicuous  character  of  the  vein 
croppings  and  to  the  equally  inconspicuous  appearance  of  the  dark- 
brown,  powdery  gold  set  free  by  the  oxidation  of  tellurides.  As  soon 
as  the  true  character  of  the  veins  was  ascertained  the  development  of 
the  district  proceeded  rapidly.  In  1894,  when  the  first  survey  was 
made,  the  production  was  a  little  less  than  $3,000,000,  but  the  next 
year  this  amount  was  more  than  doubled,  and  in  1900  the  maximum 
production  of  a  little  over  $18,000,000  was  attained.  In  1901  and 
1902  the  production  declined  slowly,  and  dropped  the  next  year  to 
$13,000,000.  The  sudden  decrease  in  1903  was  to  some  extent  brought 
about  by  the  impoverishment  of  several  mines,  but  the  labor  troubles 
of  that  year  had  also  much  to  do  with  it.  From  August,  1903,  to 
the  summer  of  1904  many  mines  experienced  more  or  less  difficulty 
from  this  cause.  It  is  probable,  however,  that  the  output  for  the 
current  year  will  show  a  considerable  increase  over  that  of  1903. 


LINDGREN  AND"] 
RANSOME. 


PRODUCTION.  9 

Production  of  the  Cripple  Creek  district  according  to  the  reports  of  the  Director  of  the  Mint.® 


Year. 

Gold. 

Silver. 

1891 

$449 

Fine  dunces. 

1892 

583,  010 

1893 

2,  010,  367 

5,019 

1894       

2,  908,  702 

25,  900 

1895    

6,  879,  137 

70,  448 

1896 

7,  512,  911 

60,  864 

1897 

10,  139,  709 

57,  297 

1898 

13,  507,  244 

68,  195 

1899      

-  15,658,254 

82,  520 

1900        

18,  073,  539 

80,  166 

1901   

17,  261,  579 

90,  884 

1902  

16,  912,  783 

62,  690 

1903 

12,  967,  338 

42,  210 

Total 

124,  415,  022 

646,  193 

The  total  dividends  can  not  be  ascertained  on  account  of  the  many 
individuals  and  small  companies  operating  in  the  district.  The  divi- 
dends of  the  larger  companies,  it  is  stated,  amounted  to  $32,752,000  to 
the  end  of  1903.  In  that  year  it  is  reported  that  $1,716,000  was  paid 
by  fourteen  mines,  Portland,  Strong,  and  Stratton's  Independence 
leading,  with  $360,000,  $300,000,  and  $250,000,  respectively. 

MIXING  AKB  METALLURGY. 

At  the  present  time  there  are  about  300  mines  in  the  district,  though 
many  of  these  are  idle  and  others  are  consolidated  into  larger  proper- 
ties. The  number  of  shafts  1,000  feet  or  more  in  depth  is  about  22; 
of  these  the  Lillie  is  the  deepest,  having  attained  1,500  feet.  Compar- 
atively few  of  the  mines  are  pumping,  the  district  being  drained  by 
tunnels,  as  will  be  described  in  a  following  paragraph.  The  motive 
power  for  hoisting  is  ordinarily  steam,  electric  power  being  used  only 
in  smaller  shafts.  The  mining  methods  employed  present  few  features 
of  particular  interest.  The  width  stoped  ranges  from  3  to  50  feet  or 
more.  The  stopes  are  sometimes  filled,  but  are  often  left  open  after 
the  broken  rock  between  levels  has  been  drawn  off.  Operations  are 
facilitated  by  the  great  hardness  of  the  rock,  stopes  200  feet  or  more 
in  height  sometimes  standing  for  years.  To  an  annual  production  of 
$18,000,000  (1900)  corresponded  a  maximum  output  of  about  600,000 
tons.  The  ores  are  not  adapted  to  concentrating  by  ordinary  means. 

«  The  figures  given  in  the  Mint  reports  are  considerably  lower  than  those  usually  quoted  in  mining 
journals  and  popular  descriptions  of  the  district. 


10  RESURVEY    OF    CRIPPLE    CREEK    DISTRICT.  [BULL. 254. 

Hand  sorting  and  washing,  the  latter  in  order  to  separate  the  fines,  are 
the  methods  employed.  More  care  is  now  taken  than  formerly,  but 
at  many  places  there  is  still  room  for  improvement. 

The  district  contains  many  large  mines  operated  by  strong  compa- 
nies, but  the  system  of  leasing  to  individuals  and  small  companies,  with 
royalty  charges  of  15  to  25  per  cent  of  the  net  output,  remains  a 
conspicuous  feature.  At  the  present  time  the  mines  of  the  north- 
western and  northeastern  parts  of  the  district  are  only  slightly  pro- 
ductive. Among  the  formerly  highly  productive  mines  in  this  section 
may  be  mentioned  the  Victor,  Isabella,  Wild  Horse,  Damon,  Logan, 
Orpha  May,  Pharmacist,  C.  O.  D.,  Gold  King,  and  Anchoria-Leland. 
The  southwest  quarter  of  the  district  contains  the  active  and  impor- 
tant El  Paso,  Mary  McKinney,  and  Elkton  mines,  but  the  maximum 
output  during  the  last  few  years  has  come  from  the  southeastern  por- 
tion, within  which  are  the  Portland,  Gold  Coin,  Ajax,  Strong,  Golden 
Cycle,  .Vindicator,  and  Last  Dollar  mines.  The  Portland  mine  has  for 
some  time  been  the  heaviest  producer  in  tonnage  as  well  as  in  value. 
Its  output  is  from  60,000  to  90,000  tons  per  annum.  In  1903  this 
mine  produced  $2,600,000. 

The  metallurgical  history  of  the  camp  is  interesting.  Beginning 
with  local  amalgamating  mills,  the  practice  soon  changed  to  local 
chlorination  and  cyanide  plants.  It  was  soon  found,  however,  that 
better  situations  would  be  found  in  the  valleys,  and  at  present  a  very 
large  part  of  the  tonnage  is  shipped  to  chlorination  and  cyanide  works 
at  Colorado  City  and  Florence.  About  a  sixth  of  the  output,  com- 
prising the  higher  grade  ores,  is  sent  to  smelting  works  at  Denver 
or  Pueblo.  A  still  smaller  amount  is  treated  in  a  local  chlorination 
plant  near  Victor.  While  in  former  years  the  practice  leaned  more 
toward  the  cyanide  process,  the  bulk  of  the  ore  is  now  treated  in  large 
chlorination  mills  with  automatic  roasters  and  revolving  barrels.  It 
has  always  been  found  necessary  to  roast  all  except  the  completely 
oxidized  ores.  At  the  present  time  there  are  in  the  district  two  small 
mills  in  which  the  cyanide  process  is  used  without  previous  roasting, 
and  which  are  thus  enabled  to  work  ores  containing  as  little  as  $5  a 
ton  in  gold.  The  extent  of  these  low-grade  ores  is  not  yet  fully 
demonstrated.  Regarding  the  value  of  the  ore,  see  page  21. 

Treatment  charges  at  the  mills  fluctuate  somewhat,  but  usually  range 
from  $7  to  $13  a  ton,  according  to  the  tenor  of  the  ore;  in  the  early 
part  of  1904  the  prices  were  reduced,  it  is  reported,  and  ranged  from 
$5. 50  to  $10  per  ton.  Recently  they  have  again  been  increased.  On  the 
whole  the  mining  and  milling  expenses  are  very  high  at  Cripple  Creek 
compared  with  those  of  other  localities — western  Australia,  for  exam- 
ple, where  similar  ores  and  conditions  prevail.  Few  of  the  large 
mines  seem  to  have  reduced  total  expenses  below  $16  per  ton. 


TOPOGRAPHY  AND  GENERAL  GEOLOGY.  11 


RANSOME. 


TOPOGRAPHY. 

The  mines  are  situated  in  a  group  of  bare,  rounded  hills  forming 
part  of  the  high  plateau  extending  south  westward  from  Pikes  Peak,  and 
are  only  about  10  miles  distant  from  that  prominent  landmark.  The 
elevations  range  from  9,000  to  nearly  11,000  feet  above  sea,  the  highest 
point  in  the  district  being  Trachyte  Mountain  (10,863  feet).  Bull 
Hill  and  Bull  Cliff  are  but  slightly  lower.  The  drainage  is  chiefly 
southward  toward  the  Arkansas  River.  The  district  contains  two 
important  towns.  Cripple  Creek  is  situated  on  the  northwest  side  of 
the  producing  area,  while  Victor,  3  miles  distant,  lies  on  the  south- 
west edge  of  the  same  area.  Two  railroads  connect  the  district  with 
Colorado  Springs,  the  Colorado  Midland  circling  around  the  north 
side  of  Pikes  Peak,  while  the  Short  Line  descends  to  the  valley  along 
the  picturesque  eastern  slope  of  the  same  mountain.  The  Florence  and 
Cripple  Creek  Railroad  runs  southward  to  Florence  in  the  Arkansas 
Valley.  An  excellent  system  of  electric-car  lines  connects  the  towns 
with  all  the  important  mines. 

GENERAL   GEOLOGY. 

FIRST   GEOLOGICAL   SURVEY   OF   THE    DISTRICT. 

When  Mr.  Whitman  Cross  made  his  careful  study  of  the  geology  of 
the  Cripple  Creek  district,  ten  years  ago,  mining  had  barely  begun 
and  the  various  hills  were  not,  as  now,  perforated  by  deep  under- 
ground workings.  That  his  work  has  in  general  stood  the  test  of 
subsequent  underground  exploration  and  continues  to  be  highly 
regarded  in  the  district  is  convincing  proof  of  its  high  quality.  .  Later 
workers,  however  they  may  modify  or  amplify  his  results,  should 
acknowledge  their  debt  to  the  pioneer  who  first  deciphered  the 
history  of  this  volcanic  district.  The  account  of  general  geology,  as 
given  by  Cross,  ma}7  be  very  briefly  summarized  as  follows: 

The  Cripple  Creek  hills  lie  near  the  eastern  border  of  an  elevated 
and  much  dissected  plateau  which  slopes  gently  westward  for  40 
miles,  from  the  southern  end  of  the  Colorado  Range,  dominated  by 
Pikes  Peak,  to  the  relatively  low  hills  connecting  the  Mosquito  and 
Sangre  de  Cristo  ranges.  The  prevailing  rocks  of  this  plateau  are 
granites,  gneisses,  and  schists.  The  granites  inclose  masses  of  Algon- 
kian  quartzite  and  are  therefore  post-Archean.  But  they  are  older 
than  the  only  Cambrian  sediments  known  in  Colorado,  and  on  the 
Cripple  Creek  map  have  been  indicated  as  Algonkian.  During 
Tertiary  time  volcanic  eruptions  broke  through  these  ancient  rocks  at 
several  points  and  piled  tuffs,  breccias,  and  lavas  upon  the  uneven 
surface  of  the  plateau.  The  eruptive  rocks  of  the  Cripple  Creek 
district  are  the  products  of  one  of  the  smaller  isolated  volcanic  centers 


12  RESURVEY    OF    CRIPPLE    CREEK    DISTRICT.  [BULL.  254. 

of  this  period,  a  center  characterized  by  the  eruption  of  phonolite, 
which  does  not  occur  elsewhere  in  this  general  region. 

The  most  voluminous  products  of  the  Cripple  Creek  volcano  now 
preserved  are  tuffs  and  breccias.  They  occupy  a  rudely  elliptical 
area  in  the  center  of  the  district,  about  5  miles  long  in  a  northwest- 
southeast  direction  and  about  3  miles  wide.  According  to  Cross  these 
breccias  and  tuffs  rest  in  part  upon  an  earlier  flow  of  andesite,  but 
mainly  upon  an  unevenly  eroded  surface  of  the  granites  and  schists, 
although  along  the  southwest  edge  of  the  area  the  contact  was  found 
to  be  so  steep  as  u  to  support  the  idea  that  the  central  vent  or  vents  of 
the  volcano  were  adjacent  to  this  line."  The  breccia  is  much  indurated 
and  altered,  but  was  thought  by  Cross  to  consist  mainly  of  andesitic 
fragments,  although  it  was  recognized  that  fragments  of  phonolite  are 
locally  abundant.  The  most  characteristic  massive  rock  of  the  Cripple 
Creek  volcano  is  phonolite,  which  was  erupted  at  several  periods  and 
more  abundantly  than  any  other  type.  It  occurs  as  dikes  and  masses, 
not  only  in  the  breccia  but  in  the  surrounding  granitic  rocks. 

The  general  succession  of  igneous  rocks,  according  to  Cross,  is  as 
follows:  The  earliest  rocks  were  andesites  containing  some  orthoclase. 
Then  came  a  series  of  allied  phonolitic  rocks,  rich  in  alkalies  and  mod- 
erately rich  in  silica,  together  with  some  andesites.  Among  them  are 
trachytic  phonolite,  nepheline-syenite,  syenite-porphyry,  phonolite, 
mica-andesite,  and  pyroxene-andesite.  Phonolite  was  erupted  at  sev- 
eral periods.  The  nepheline-syenite  he  considered  as  probably  younger 
than  the  trachytic  phonolite.  At  the  close  were  intruded  a  small  num- 
ber of  narrow  dikes  of  basic  rocks,  the  so-called  basalts,  which  contrast 
very  markedly  with  the  phonolite. 

MODIFICATIONS   OF   EARLIER   RESULTS. 

In  the  course  of  the  present  investigation  the  geology  of  the 
district  has  been  entirely  remapped  upon  the  carefully  revised  topo- 
graphic base.  The  granites,  gneisses,  and  schists  have  been  differen- 
tiated and  outlined  in  greater  detail  than  was  practicable  in  the  earlier 
investigation.  The  oldest  rocks  in  the  district  are  muscovite-  and 
fibrolite-schists.  These  are  closely  associated  with  the  fine-grained 
granitic  gneisses  such  as  underlie  most  of  the  town  of  Cripple  Creek. 
This  gneiss,  in  the  earlier  report,  was  mapped  partly  as  schist  and 
partly  as  granite.  Both  gneiss  and  schist  are  cut  by  a  reddish  granite 
which  occupies  a  considerable  area  extending  from  Anaconda  west- 
ward beyond  the  limits  of  the  area  studied.  This  granite  is  well 
exposed  along  Cripple  Creek  in  the  vicinity  of  Mound. 

A  second  type  of  granite  distinguished  and  mapped  is  the  coarsely 
porphyritic  rock  referred  to  by  Cross  as  the  Pikes  Peak  type  of  granite. 
This  rock  occupies  over  half  of  the  district  and  is  the  prevailing  type 


LINDGREN  AND 
BANSOME. 


]  GENERAL    GEOLOGY.  13 

along  the  northern,  eastern,  and  southern  borders  of  tut,  area.  It  is 
well  exposed  on  Squaw  Mountain  and  is  the  granite  of  the  El  Paso, 
Elkton,  Ajax,  Portland,  Independence,  and  Gold  Coin  mines.  Of 
these  two  kinds  of  granite  the  Cripple  Creek  variety  is  probably  the 
younger.  The  Cripple  Creek  gianite,  the  gneiss,  and  the  schist 
together  form  a  wedge-shaped  area  projecting  into  the  Pikes  Peak 
granite  from  the  west.  The  center  of  volcanic  disturbance  practically 
coincides  with  the  point  of  this  wedge. 

The  present  investigation  indicates  some  necessary  modifications  of 
the  earlier  report  in  the  way-  of  stronger  emphasis  on  the  intimate 
genetic  relationship  of  the  rocks.  The  "phonolite,"  "nephelinex- 
syenite,"  "trachytic  phonolite,"  "syenite-porphyry,"  and  "andesites" 
of  Cross  are  all  very  closely  related  and  have  been  found  to  be  in  most 
cases  connected  by  intermediate  types.  They  are  clearly  all  slightly 
divergent  eruptive  facies  of  one  general  magma  characterized  chemi- 
cally by  containing  from  9  to  15  per  cent  of  potash  and  soda,  the  soda 
being  always  somewhat  higher  than  the  potash,  particularly  when  the 
comparison  is  made  by  molecular  ratios.  None  of  the  massive  rocks 
can  properly  be  called  andesite,  and  although  it  can  not  be  affirmed 
that  andesitic  fragments  are  entirely  absent  from  the  usually  much 
altered  volcanic  breccia,  the  term  "andesitic  breccia"  does  not  seem 
applicable  to  this  formation  as  a  whole.  It  would  be  more  accurate  to 
describe  it  as  a  phonolitic  breccia,  although  in  places  it  consists  chiefly 
of  particles  of  the  older  rocks  through  which  the  Tertiary  eruptives 
broke. 

None  of  the  massive  rocks  erupted  from  the  Cripple  Creek  volcanic 
center  and  now  preserved  in  the  district  show  any  evidence  of  having 
been  surface  flows.  They  are  for  the  most  part  intrusive  porphyries, 
ranging  in  texture,  however,  from  the  granular  so-called  nepheline- 
syenite  near  the  town  of  Independence  to  the  nearly  aphanitic  phono- 
lite  of  the  smaller  dikes  and  sheets.  Most  of  them  will  come  under 
the  designations  phonolite,  trachytic  phonolite,  trachydolerite,  and 
alkali-syenite.  The  extensive  underground  workings  show  that  the 
" nepheline-syenite "  does  not  cut  the  "trachytic  phonolite,"  but  that 
the  two  rocks  represent  textural  and,  to  some  extent,  mineralogical 
facies  of  the  same  mass,  while  the  trachytic  phonolite  in  turn  may  pass 
into  phonolite.  The  trachytic  phonolite  is  in  some  instances  cut  by. 
dikes  of  phonolite,  showing,  as  Cross  has  already  pointed  out,  that  the 
phonolitic  intrusions  were  not  all  synchronous. 

While  it  is  undoubtedly  true  that  much  of  the  breccia  in  the  north- 
eastern part  of  the  volcanic  area  rests  upon  a  very  uneven  surface  of 
granite,  gneiss,  and  schist,  the  results  of  field  work  during  the  last 
season,  favored  by  deep  workings  not  in  existence  when  the  district 
was  originally  surveyed,  have  emphasized  the  fact  that  the  breccia 
lying  southwest  of  a  general  northwest-southeast  line  drawn  through 


14  RESCTRVEY    OF    CRIPPLE    CREEK    DISTRICT.  [BULL.  254. 

Big  Bull  Mountain  and  Gold  Hill  occupies  a  chasm  of  profound  depth 
in  the  fundamental  rocks  of  the  region.  From  the  Conundrum  mine 
on  the  western  slope  of  Gold  Hill  to  Stratton's  Independence  mine  on 
the  south  slope  of  Battle  Mountain  the  contact  plunges  steeply  down, 
with  dips  ranging  in  general  from  70°  to  vertical.  In  some  instances 
the  granite  walls  of  this  chasm  actually  overhang  the  breccia.  It  is 
probable  that  this  entire  southwest  contact  represents  a  part  of  the 
wall  of  the  great  pit  formed  by  the  volcanic  explosions  that  produced 
the  breccia.  It  is  further  probable  that  an  arm  or  branch  of  this 
volcanic  abyss,  now  filled  with  breccia  and  intrusive  rocks,  extends 
northeastward  past  Bull  Cliff  and  the  town  of  Altman. 

ECONOMIC  GEOLOGY. 

EARLIER   WORK. 

To  the  excellent  work  of  Mr.  R.  A.  F.  Penrose,  jr.,  apply  statements 
similar  to  those  made  in  the  discussion  of  the  purely  geological  branch 
of  the  subject.  Few  shafts  had  then  attained  a  depth  of  400  feet,  and 
most  of  the  exposures  were  masked  by  surface  oxidation.  It  would 
be  surprising,  in  view  of  the  facilities  created  by  the  later  develop- 
ment of  hundreds  of  mines,  if  a  subsequent  investigation  should  not 
bring  out  some  slight  modifications  of  earlier  results. 

EXTENT   OF   PRODUCTIVE   TERRITORY. 

There  is  nothing  in  the  history  of  the  district  since  1894  warranting 
any  extension  of  the  bounds  of  the  productive  territory  as  then  known. 
Now,  as  then,  a  circle  of  3  miles  radius  described  from  the  summit  of 
Gold  Hill  would  include  all  deposits  of  known  or  prospective  value, 
while  the  really  important  mines  would  be  embraced  by  a  circle  of  about 
half  that  radius,  with  its  center  near  the  summit  of  Raven  Hill.  That 
scattered  deposits  of  greater  or  less  value  may  be  found  in  outlying 
portions  of  the  district  is  by  no  means  improbable.  But  the  close 
dependence  of  the  typical  Cripple  Creek  ores  upon  the  main  volcanic 
center,  and  the  consequent  remarkable  compactness  of  the  gold-bearing 
area,  are  features  highly  characteristic  of  the  district  and  are  likely 
always  to  remain  so. 

The  greater  part  of  the  ore  has  undoubtedly  come  from  the  central 
area  of  breccia,  particularly  from  that  part  of  this  area  in  which  the 
breccia  extends  to  great  depth.  Very  productive  ore  bodies  have 
been  found,  however,  in  the  granitic  rocks,  usually  within  1,000  feet 
of  the  steep  contact  limiting  the  breccia  on  the  southwest.  The  im- 
portant Beacon  Hill  mines,  with  ore  bodies  nearly  three-quarters  of  a 
mile  from  this  contact,  are  exceptional,  and  are  probably  genetically 
connected  with  the  intrusive  mass  of  phonolite  forming  the  core  of 
the  hill. 


ECONOMIC  GEOLOGY.  15 


UNDERGROUND  DEVELOPMENT. 

At  the  time  of  the  earlier  survey  the  deepest  shafts,  those  of  the 
Moose,  Pharmacist,  and  Anna  Lee  mines,  were  down  only  about  400 
feet,  while  few  of  the  other  mines  were  over  200  feet  in  depth.  Many 
subsequently  prominent  mines  were  then  mere  prospects  or  had  not 
been  located. 

The  deepest  shaft  at  present  is  the  Lillie,  which  is  over  1,500  feet 
deep,  although  the  Stratton's  Independence  shaft,  1,400  feet  deep,  has 
the  lowest  sump  in  the  district.  The  American  Eagle  shaft  is  nearly 
as  deep  as  the  Lillie,  while  there  are  about  twenty  other  shafts  over 
1,000  feet  in  depth,  and  at  least  100  shafts  deeper  than  the  deepest 
workings  existing  in  1894.  As  regards  absolute  elevations,  the  Gold 
Hill  shafts  are  scarcely  down  to  a  level  of  9,000  feet  above  sea;  the 
Elkton,  El  Paso,  and  Lillie  shafts  descend  to  8,750  feet;  Stratton's 
Independence  reaches  the  lowest  level  at  8,450  feet;  while  the  Gold 
Coin  shaft,  at  8,550  feet,  is  of  interest  from  the  fact  that  the  deepest 
ore  shoot  in  the  district  is  now  being  stoped  from  its  twelfth  level. 

The  amount  of  drifting  and  crosscutting  accomplished  since  the 
earlier  survey  is  more  than  commensurate  with  the  increased  number 
and  depth  of  the  shafts,  and  the  district  is  further  intersected  in  vari- 
ous directions  and  at  different  levels  by  two  long  tunnels  run  for 
drainage  purposes  and  by  a  dozen  or  more  extensive  adits,  many  of 
which  have  their  portals  in  the  granitic  rocks  and  extend  well  into  the 
central  part  of  the  breccia  area. 

BRIEF   REVIEW   OF   THE   MINES. 

The  productive  district,  as  stated  above,  is  practically  covered  by  the 
area  of  a  circle  3i  miles  in  diameter.  The  center  of  this  circle  would  be 
located  halfway  between  Raven  Hill  and  Bull  Hill,  and  the  towns  of 
Cripple  Creek,  Victor,  and  Cameron  would  be  situated  on  its  peripheiy . 
A  very  few  mines— notably  the  Galena  and  the  Fluorine — and  many 
prospects  lie  outside  of  this  area. 

The  culminating  points  of  the  district  are  found  in  a  ridge  of  higji 
and  bare  hills  that  extends  in  a  northwest-southeast  direction  and 
divides  the  waters  flowing  into  Cripple  Creek  and  Wilson  Creek  on  the 
southwest  from  those  joining  Spring  Creek  and  Grassy  Creek  on  the 
north.  From  northwest  to  southeast  the  following  hills  mark  this 
divide:  Mineral  Hill,  Carbonate  Hill,  and  Tenderfoot  Hill,  north 
or  northeast  of  Cripple  Creek;  Globe  Hill,  Ironclad  Hill,  and  Bull 
Hill,  the  latter  being  near  the  center  of  the  district  and  equidistant 
from  Cripple  Creek  and  Victor;  the  ridge  is  continued  by  Bull  Cliff 
and  Big  Bull  Mountain,  the  latter,  really  outside  of  the  productive 
area,  being  the  highest  point  in  this  dividing  range  of  hills.  Its  ele- 
vation is  10,826  feet.  Three  long  spurs  project  to  the  southwest  from 


16  RESURVEY    OF    CRIPPLE    CREEK    DISTRICT.  [BULL.  254. 

the  dividing  range  separating  the  deep  trenches  of  Cripple  Creek, 
Squaw  Gulch,  Arequa  Gulch,  and  Wilson  Creek;  the  first,  called  Gold 
Hill,  rises  directly  east  of  Cripple  Creek;  the  second  is  Raven  Hill, 
being  continued  to  the  southwest  by  the  lower  spur  of  Guyot  and 
Beacon  hills;  the  third  is  Battle  Mountain,  continued  by  the  almost 
equally  high  salient  of  Squaw  Mountain. 

The  important  mines  are  situated  in  this  region  of  sharply  accentu- 
ated topography.  As  has  been  several  times  emphasized,  the  volcanic 
area  practically  coincides  with  the  hills  and  ridges  just  described  and 
is  surrounded  on  all  sides  by  granitic  rocks. 

Globe  and  Ironclad  hills  and  Gold  and  Raven  hills  consist  chiefly  of 
heavy  masses  of  breccia,  and  were  scenes  of  great  activity  during  the 
early  years  of  the  district.  Near  Poverty  Gulch,  just  northeast  of 
Cripple  Creek,  is  the  Abe  Lincoln,  not  a  large  mine,  but  still  actively 
worked  with  satisfactory  results.  Higher  up  are  the  Gold  King,  with 
dividend  records  of  $150,000,  and  the  C.  O.  D.,  with  a  reported  pro- 
duction of  $600,000  and  dividends  of  $150,000.  Both  were  idle  in  1904 
and  have  attained  their  eighth  or  ninth  levels. 

On  the  summit  of  Globe  Hill  are  the  Stratton  properties  of  Ply- 
mouth Rock  and  Globe  mines,  in  which  extensive  low-grade  mineraliza- 
tion without  many  sharply  defined  veins  seems  to  be  the  rule. 
Adjoining  is  the  property  of  the  Homestake  Company,  including  the 
Ironclad  mine,  where  direct  cyaniding  of  oxidized  surface  ores  is  now 
carried  on  in  a  mill  erected  on  the  property. 

Gold  Hill  is  crowned  by  the  Anchoria-Leland  mine,  with  a  produc- 
tion of  over  $1,000,000  and  dividends  of  $198,000.  The  shaft  is  1,100 
feet  deep.  The  adjoining  Moon- Anchor  has  paid  dividends  of  $261,000, 
and  the  Half  Moon  (Matoa  G.  M.  Co.)  has  a  gross  production  of  $650,000 
to  its  credit,  but  is  reported  to  have  paid  only  a  small  amount  in  divi- 
dends. None  of  these  mines  is  being  worked  at  present,  except  on  a 
small  scale  by  lessees. 

On  the  western  slope  is  the  Midget  mine,  actively  worked  at  present, 
with  a  depth  of  800  feet,  a  total  production  of  $662,000,  and  dividends 
of  $195,000.  The  Conundrum,  in  the  same  vicinity,  is  likewise  worked 
with  good  results  to  a  depth  of  600  feet.  The  Midget,  like  the  mines 
described  above,  follows  a  vein  in  breccia,  while  the  Conundrum  is  min- 
ing on  a  "basalt"  dike  in  granite,  close  to  the  contact  of  the  breccia. 

In  the  deep  gulch  between  Gold  Hill  and  Raven  Hill  are  situated 
the  Anaconda,  Doctor-Jack  Pot,  and  Mary  McKinney  mines,  all  work- 
ing on  sheeted  zones  forming  lodes  in  the  breccia.  The  Anaconda  pro- 
duced about  $1,000,000,  chiefly  from  upper  levels,  and  is  now  idle. 
The  Mary  McKinney  is  one  of  the  most  successful  mines  worked  at 
present  in  the  district.  Its  depth  is  600  feet.  The  Doctor-Jack  Pot 
has  $4,000,000  to  its  credit  and  likewise  a  handsome  dividend  record. 


]  THE    MINES.  17 

The  shaft  is  only  700  feet  deep,  water  having  until  now  prohibited 
deeper  sinking. 

The  breccia-granite  contact  is  found  on  Guyot  Hill  a  short  distance 
south  of  the  Mary  McKinney.  The  extreme  spur  of  Raven  Hill, 
called  Beacon  Hill,  is  formed  of  an  intrusion  of  phonolite  in  granite, 
and  about  this  outlying  volcanic  center  cluster  a  group  of  veins  of 
great  production  and  promise.  On  the  eastern  side  of  the  hill  are 
located  the  Prince  Albert,  Gold  Dollar,  and  others,  not  active  pro- 
ducers at  present,  while  on  the  western  side  lie  the  El  Paso,  C.  K. 
&  K,  and  Old  Gold  mines,  with  their  narrow  but  extremely  rich  fis- 
sure veins  in  granite,  now  actively  and  successfully  worked. 

A  great  number  of  smaller  mines  have  been  worked  on  veins  cut- 
ting the  breccia  of  Raven  Hill.  The  famous  Elkton  mine  is  situated  in 
the  deep  hollow  between  Raven  Hill  and  Battle  Mountain.  It  has  been 
working  on  an  exceptionally  long  vein,  partly  contained  in  breccia, 
partly  in  granite,  and  generally  following  a  '  'basalt"  dike.  The  produc- 
tion approaches  $6,000,000,  and  the  depth  attained  is  about  900  feet, 
excessive  water  having  formed  a  serious  obstacle  to  deeper  sinking. 
Dividends  amount  to  $1,200,000.  The  Moose  mine,  situated  higher 
up  on  the  slope  of  Raven  Hill,  had  a  good  ore  shoot,  from  which 
$500,000  was  obtained. 

Continuing  northwest,  we  soon  attain  the  summit  of  Bull  Hill,  which 
affords  a  magnificent  panorama,  not  only  of  the  whole  camp,  but  of 
a  large  part  of  the  State  of  Colorado.  Toward  the  east,  and  5,000  feet 
lower,  spread  the  great  plains  at  the  foot  of  the  Rocky  Mountains; 
westward  the  Sangre  de  Cristo,  Collegiate,  and  Mosquito  ranges — a 
snowy  and  jagged  line  of  ramparts — define  the  distant  horizon. 

A  multitude  of  small  mines  occupy  the  southwestern  slope  of  Bull 
Hill.  On  the  northwestern  side  an  area  of  brecciated  granite  appears 
among  the  volcanic  rocks,  and  in  this  formation  is  situated  the  Wild 
Horse  mine.  This  lode,  which  has  been  worked  to  a  depth  of  1,250 
feet,  has  produced  over  $1,000,000,  but  is  now  operated  only  by 
lessees.  A  number  of  smaller  producers  may  be  found  on  the  north- 
ern slope,  toward  Cameron,  among  them  the  Damon,  Jerry  Johnson, 
W.  P.  H.,  and  Pinnacle. 

Those  who  have  followed  this  description  on  a  map  will  have  noticed 
that  the  mines  are  chiefly  situated  on  the  periphery  of  a  circular  area, 
the  central  part  of  which,  comprising  the  upper  part  of  Squaw  Gulch, 
has  thus  far  yielded  very  little.  Few  strong  veins  have  been  met 
with  in  this  part  of  the  breccia,  but,  on  the  other  hand,  the  devel- 
opments in  depth  are  not  extensive. 

On  the  east  and  southeast  side  of  Bull  Hill  begins  that  most  impor- 
tant belt  of  lodes  which  extends  southward  to  Victor  and  includes  the 
richest  group  of  producers  in  the  camp.  A  characteristic  feature  of 
Bull.  254—05 2 


18  RESURVEY    OF    CRIPPLE    CREEK    DISTRICT,  [BULL.  254. 

this  belt  is  the  intrusion  into  the  breccia  of  thick  masses  of  trachytic 
phonolite  and  syenitic  rocks. 

With  few  exceptions  the  veins  of  this  belt  strike  north-northwest. 
We  may  begin  the  description  with  the  system  of  linked  veins,  3,000 
feet  long,  covered  by  the  Isabella  and  Victor  mines.  The  last-named 
mine,  on  the  southern  end  of  the  system,  is  situated  just  below  the 
western  slope  of  Bull  Cliff.  It  has  been  worked  to  a  depth  of  over 
1,000  feet,  has  produced  about  $2,200,000,  and  has  paid  dividends 
amounting  to  $1.150,000.  The  Isabella  has  attained  a  depth  of  1,127 
feet,  produced  $3,200,000,  and  paid  dividends  of  $600,000.  Both  mines 
lost  their  pay  shoot  in  depth. 

The  small  but  rich  cross  veins  of  the  Empire  State,  Burns, 
Pharmacist,  and  Zenobia  connect  this  vein  system  with  that  of  the 
Stratton  mines  on  Bull  Hill.  South  of  the  Burns  begins  the  great 
Vindicator  vein  system,  traced  southeasterly  for  a  mile  through  the 
Findley,  Hull  City,  Vindicator,  Lillie,  and  Golden  Cycle  mines.  The 
Hull  City  and  the  Lillie  have  each  produced  over  $1,000,000,  the  Vin- 
dicator and  Golden  Cycle  over  $2,000,000  each,  all  with  correspond- 
ing dividend  records.  The  Lillie  is  deepest,  having  attained  1,500  feet. 
Next  in  depth  is  the  Vindicator,  1,200  feet.  All  of  them,  except  the 
Lillie,  are  still  actively  worked.  In  the  whole  system  water  has  been 
and  is  still  a  source  of  trouble.  The  deepest  mine  evidently  drains 
all  the  others  in  this  vicinity. 

The  Stratton  properties  on  Bull  Hill,  with  the  Logan,  Orpha  May, 
and  Pikes  Peak  veins,  on  which  maximum  depths  of  1,200  and  1,500 
feet  have  been  attained,  are  now  worked  only  to  a  slight  extent, 
whereas  in  the  early  days  of  the  camp  they  were  highly  productive. 

This  vein  system  is  continued  southward  in  the  Last  Dollar  mine, 
now  working  at  a  depth  of  1,270  feet.  The  production  exceeds 
$1,000,000.  South  of  the  Last  Dollar  the  veins  enter  the  Modoc 
ground,  a  mine  worked  for  a  long  time  and  with  gratifying  success. 
The  Blue  Bird,  an  old-time  producer,  is  situated  a  short  distance  west 
of  the  Last  Dollar. 

South  of  the  Modoc  is  the  Battle  Mountain  vein  system,  crossing 
from  the  granite  into  the  breccia,  with  general  northerly  or  north- 
northwesterly  directions,  and  distinguished  by  heavy  production 
and  ore  bodies  of  imposing  size.  None  of  the  veins  are  of  great 
length,  and  the  whole  system  extends  scarcely  a  mile  along  the  strike 
of  the  veins.  The  veins  can  not  be  directly  connected  with  others 
already  described,  though,  in  its  general  trend,  the  system  heads 
toward  the  Dexter,  Blue  Bird,  and  Moose  veins. 

Beginning  on  the  southwestern  side,  we  first  come  to  the  Gold  Coin 
mine,  the  veins  of  which  are  in  granite;  one  of  them  is  successfully 
worked  at  present  at  a  depth  of  1,200  feet.  The  total  production 
approaches  $6,000,000;  the  dividends  paid  exceed  $1,000,000.  North 


LINOGREN  AND~|  rivcr^     T\lT-\n?Q  1  Q 

RANSOME.        J  THE     MINES.  iy 

of  the  Gold  Coin  is  the  Ajax,  working  partly  in  veins,  partly  in  large, 
irregular  ore  bodies  in  the  granite.  The  total  production  is  very  con- 
siderable. The  depth  attained  is  1,200  feet. 

Between  this  and  the  Portland  vein  system,  almost  within  the  town 
of 'Victor,  are  the  Granite,  Dillon,  and  Dead  Pine  veins.  They  are 
worked  at  present  at  depths  of  from  800  to  1,000  feet. 

The  Portland  vein  system  begins  on  the  south  at  the  Strong  mine, 
now  worked  at  a  maximum  depth  of  900  feet,  on  a  vein  in  granite 
that  follows  a  "  basalt"  dike,  which  is  in  places  accompanied  by  a 
phonolite  dike.  The  mine  is  an  unusually  regular  and  profitable 
producer,  the  total  dividends  since  1892  amounting  to  $2,500,000. 

The  veins  of  Stratton's  Independence  run  about  parallel  to  those  of 
the  Strong,  a  few  hundred  feet  eastward.  They  extend  from  the 
granite  into  the  breccia,  following  for  some  distance  a  phonolite  dike. 
The  production  of  this  mine  amounts  to  over  $11,000,000,  with  a  divi- 
dend record  of  $4,000,000  since  1899.  At  present  the  company  is 
leasing  the  various  levels  to  tributers.  From  the  two  properties  last 
described  the  vein  systems  continue  into  the  Portland  mine,  but  in 
the  northern  part  of  that  great  property  are  replaced  by  another  and 
still  richer  aggregate  of  veins,  the  Captain  system.  The  Portland  is, 
beyond  question,  the  most  prominent  mine  of  the  Cripple  Creek  dis- 
trict. Its  total  production  from  1894  to  the  end  of  1903  amounted  to 
$18,000,000,  derived  from  466,000  tons  of  ore  (both  in  round  figures), 
from  which  $4,600,000  has  been  paid  in  dividends,  the  remainder  going 
to  acquirement  of  territory,  extensive  milling  and  mining  plants,  and 
operating  expenses. 

Outside  mining  properties. — The  area  outside  of  the  principal  vol- 
canic area  contains  very  few  productive  properties,  but  it  is  by  no 
means  barren.  A  great  deal  of  money  has  been  spent  here,  usualty 
with  unsatisfactory  results.  Although  there  are  many  properties  of 
merit  and  although  much  honest  effort  has  been  made  in  this  part  of 
the  district^  it  has  long  been  the  favorite  camping  ground  of  concerns 
more  or  less  lacking  in  stability. 

The  granite  hills  west  and  south  of  the  city  of  Cripple  Creek  con- 
tain few  prospects;  phonolite  dikes  occur  in  places,  but  usually  show 
little  value.  Along  Gold  Run  and  Arequa  Gulch  prospects  with  a  little 
ore  have  been  found,  down  to  the  junction  with  Cripple  Creek,  and 
even  at  isolated  places  below  this  locality.  Grouse  Mountain,  with  its 
phonolite  cap,  shows  many  prospects  from  which  occasional  good  assays 
have  been  obtained,  but  neither  here  nor  on  Straub  and  Brind  moun- 
tains has  anything  of  permanent  value  been  developed  thus  far.  It  is 
claimed  that  ore  bodies  of  low  grade,  containing  a  few  dollars  per  ton, 
exist. 

The  breccia  caps  of  Mineral,  Carbonate,  and  Tenderfoot  hills  are 
dotted  with  prospect  dumps,  and  even  shafts  several  hundred  feet 


20  RESURVEY    OF    CRIPPLE    CREEK    DISTRICT.  [BULL.  254. 

deep.  Nothing  of  permanent  value  is  recorded  from  Mineral  Hill, 
though  fairly  productive  placers  have  been  worked  at  its  southwestern 
base,  almost  in  the  town  of  Cripple  Creek. 

On  Carbonate  Hill  the  Elkhorn  has  been  a  small  producer;  on  Ten- 
derfoot Hill  the  Friday,  Hoosier,  Black  Diamond,  and  Mollie  Kathleen 
contribute  their  parts  to  the  production.  Two  miles  north-northwest  of 
Cripple  Creek  is  the  Galena  mine,  the  vein  of  which  follows,  for  a  part 
of  its  course,  a  phonolite  dike  in  granite  and  has  a  small  output  to  its 
credit.  About  the  same  distance  north  of  the  city  is  the  small  volcanic 
center  of  Copper  and  Rhyolite  mountains.  At  the  former  the  Fluorine 
mine  has  produced  $160,000,  and  low-grade  ore  is  now  being  cyanided. 
Prospects  are  found  on  Rhyolite  Mountain,  and  in  fact  all  over  the  flat 
granite  country  between  it  and  Trachyte  Mountain.  The  Lincoln  mine, 
near  Gillette,  and  several  other  prospects  farther  south,  along  a  belt 
of  phonolite  dikes,  have  produced  a  little  ore.  It  is  claimed  that  there 
are  low-grade  veins  on  both  sides  of  Bernard  Creek,  northwest  of 
Gillette,  in  a  region  of  granite  with  occasional  dikes  and  masses  of 
phonolite.  Trachyte  Mountain,  southeast  of  Gillette,  is  covered  by 
phonolite,  and  a  little  ore  is  occasionally  found  in  veins  at  its  southern 
foot.  Some  work  has  also  been  done  on  Cow  Mountain,  about  4  miles 
northeast  of  Bull  Hill. 

The  eastern  margin  of  the  central  volcanic  area,  east  of  Victor  Pass 
and  extending  southward  across  Big  Bull  Mountain  to  Brind  Mountain, 
has  thus  far  failed  to  produce  anything  of  importance,  though  well 
covered  by  prospects.  A  survey  of 'these  outlying  parts  of  the  district 
serves  to  emphasize  strongly  the  remarkable  concentration  of  deposits 
within  the  narrow  limits  of  the  central  volcanic  area. 

CHARACTER   OF   THE   ORES. 

The  characteristic  feature  of  the  Cripple  Creek  ores  is  the  occurrence 
of  the  gold  in  combination  with  tellurium,  chiefly  as  calaverite,  but 
partly  also  as  the  more  argentiferous  sylvanite,05  and  probably  to  a 
minor  extent  as  other  gold,  silver,  and  lead  tellurides.  The  tellurides 
are  frequently  associated  with  auriferous  and  highly  argentiferous 
tetrahedrite,  with  molybdenite,  and  occasionally  with  stibnite.  While 
these  minerals  have  not  yet  been  closely  studied,  preliminary  examina- 
tion indicates  that  their  contents  in  gold  are  due  to  an  intimate  mechan- 
ical mixture  of  tellurides.  Pyrite,  while  widely  disseminated  through 
the  country  rock  and  of  common  occurrence  in  the  fissures,  is  rarely 
sufficiently  auriferous  to  constitute  ore.  Such  of  the  pyritic  ores  as 
have  been  tested  reveal  the  presence  of  tellurium,  indicating  that  the 
ore  is  a  mixture  of  pyrite  and  gold-silver  tellurides.  Galena  and 

a  Calaverite  ( AuAg)  Te2:  tellurium,  57.4  per  cent;  gold,  39.5  per  cent;  silver,  3.1  per  cent.  Sylvanitc 
(AuAg)  Te2:  tellurium,  62.1  per  cent;  gold,  24.5  per  cent;  silver,  13.4  per  cent. 


L1NBDA°NsoME.ND]  CHARACTER    OF   THE    ORES.  21 

sphalerite  occur  in  small  quantities  in  many  of  the  mines,  but  rarely 
contain  enough  of  the  precious  metals  to  form  ore.  Native  gold 
appears  to  be  absent  from  the  telluride  ores,  except  as  it  may  be  set 
free  by  the  oxidation  of  these  tellurides. 

The  usual  gangue  minerals  of  the  ores  are  quartz,  fluorite,  and  dolo- 
mite. Roscoelite  and  rhodochrosite  are  also  found  in  places.  Celestite, 
or  sulphate  of  strontium,  while  never  present  in  large  amount,  fre- 
quently occurs  as  little  acicular  crystals  in  the  quartz  vugs  of  the  lodes. 
Calcite  occurs  interstitially  in  much  of  the  breccia  near  the  ore  bodies, 
but  is  rarely  found  in  distinct  crystalline  form  with  the  ore  minerals. 
Secondary  potassium  feldspar  is  common  in  the  ores;  it  is  especially 
abundant  in  the  ores  inclosed  in  granite,  particularly  those  in  the 
Pikes  Peak  type.  This  feldspar  has  the  composition  of  orthoclase  or 
microcline,  and  is  formed  by  the  rec^stallization  of  the  original 
potassic  feldspar  contained  in  the  rocks.  In  the  granitic  ores  of  the 
Stratton's  Independence,  Portland,  Ajax,  and  Elkton  mines,  this  sec- 
ondary feldspar  is  the  principal  gangue  mineral. 

Oxidized  ores,  while  still  worked  in  many  properties,  are  of  rela- 
tively less  importance  than  when  Penrose  described  the  district. 
They  contain  the  characteristic  dull  gold,  often  in  pseudomorphous 
skeletons,  resulting  from  the  oxidation  of  the  tellurides,  associated 
with  tellurite  (tellurium  dioxide),  emmonsite  or  durdenite  (both 
hydrated  ferric  tellurites),  and  probably  other  oxidized  compounds  of 
tellurium  and  iron.  These  minerals  occur  in  association  with  kaolin, 
alunite,  and  ferruginous  clays.  The  deep  workings  of  the  present 
day  show  that  kaolin  is  always  connected  with  oxidation,  and  is  not  a 
product  of  the  original  mineralization  of  the  district,  as  was  supposed 
by  Penrose. 

The  Cripple  Creek  ores,  as  a  rule,  contain  very  little  silver,  the 
average  proportion  being  about  1  ounce  of  silver  to  10  ounces  of  gold. 
In  the  Portland  and  Stratton's  Independence  mines  the  proportion  is 
very  much  less,  the  silver  from  the  Portland  in  1901  amounting  to 
only  2.4  ounces  for  each  100  ounces  of  gold.  In  the  Blue  Bird, 
Doctor-Jack  Pot,  Conundrum,  Pointer,  and  other  mines  containing 
notable  amounts  of  tetrahedrite  or  galena,  the  proportion  of  silver 
rises  considerably  above  the  average. 

The  average  value  of  the  Cripple  Creek  ores  lies  probably  between 
$30  and  $40  per  ton.  In  some  of  the  larger  mines  the  average  value 
sinks  to  about  $25  per  ton.  From  a  lower  economic  limit  of  about 
$12  per  ton  the  values  of  individual  shipments  swing  through  a  wide 
range  up  to  ores  carrying  $3,000  or  $4,000,  or  even  $8,000,  per  ton. 
Occasionally  smaller  amounts — one  or  two  tons — have  yielded  as  much 
as  $50,000  per  ton. 


22  RESURVEY    OF    CRIPPLE    CREEK    DISTRICT.  [BULL.  254. 

STRUCTURAL    CHARACTER   OF    DEPOSITS. 

With  few  exceptions  the  ore  bodies,  of  whatever  shape,  are  causally 
connected  with  fissures,  and  most  of  them  constitute  fissure  veins  of 
various  types.  The  fissure  system  of  the  district  appears  to  radiate 
from  a  point  near  the  northern  limit  of  the  volcanic  area.  In  the 
eastern  part  the  prevailing  directions  are  northwest  or  north-northwest, 
gradually  changing  to  a  northerly  strike  in  the  southern  portion  and 
to  predominant  north-northeast  or  northeast  courses  in  the  western 
side  of  the  district. 

Individual  veins  are  rarely  over  half  a  mile  in  length,  but  linked- 
vein  systems  often  extend  for  a  mile  in  the  same  direction.  The  dip 
is  generally  veiy  steep.  The  movement  along  these  fissure  planes 
appears  in  all  cases  to  have  been  very  slight.  The  fissures  charged 
with  ore  are  sometimes  simple  veins  with  one  fracture  plane;  much 
more  commonly,  however,  they  are  composite  veins  or  lodes  which 
consist  of  several  closely  spaced  and  frequently  linked  fissures,  all 
more  or  less  ore  bearing.  A  better  expression  for  this  structural  type 
as  it  appears  in  Cripple  Creek  is  the  term  " sheeted  zone." 

TYPES   OF   DEPOSITS. 

The  most  important  types  of  auriferous  ore  bodies  occurring  in  the 
district  are: 

1.  Tabular  in  form  and  strictly  following  simple  fissures  or  sheeted 
zones.     A  subtype  comprises  lodes  in  which  the  sheeted  zone  follows 
"basalt"  or  phonolite  dikes. 

2.  Irregular  bodies  adjacent  to  fissures  and  formed  by  replacement 
and  recrystallization  of  the  country  rock — usually  granite. 

These  types  are  not  always  sharply  distinct,  but  may  be  connected 
by  deposits  of  intermediate  character. 

All  the  ore  bodies,  of  whatever  type,  exhibit  certain  common  features 
which  serve  to  distinguish  the  deposits  of  Cripple  Creek  from  those 
of  most  other  mining  districts.  In  the  first  place,  the  actual  openings 
in  the  rocks  available  for  the  deposition  of  ore  are,  as  a  rule,  remark- 
ably narrow.  In  the  second  place,  the  amount  of  material  carried  in 
the  mineralizing  solutions  and  deposited  as  gangue  and  ore  minerals 
was  comparatively  small.  In  consequence  of  these  two  conditions,  the 
district  contains  no  such  massive  veins,  solidly  filled  with  quartz  or 
other  vein  minerals,  as  are  characteristic  of  the  San  Juan  region  in 
Colorado  or  the  Mother  Lode  region  in  California.  Even  the  small 
fissures  of  the  Cripple  Creek  district  are  rarely  completely  filled,  but 
exhibit  a  characteristic  open  or  vuggy  structure.  Where  the  fractures 
are  of  unusual  width,  or  where  the  i  jcks  are  extensively  shattered,  as 
in  the  Midget  and  Moose  mines,  the  small  volume  of  available  vein 
matter  is  particularly  noticeable.  The  walls  of  such  fractures  and  the 


]  TYPES    OF    DEPOSITS.  23 

fragments  of  the  shattered  rock  are  usually  merely  coated  with  a  thin 
deposit  of  quartz,  fluorite,  and  other  minerals.  As  the  rich  tellurides 
were  usually  among  the  minerals  last  to  form,  and  are  particularly 
abundant  on  the  walls  of  the  vugs,  it  is  probable  that  had  quartz,  fluor- 
ite, or  other  gangue  minerals  been  more  abundantly  deposited  the 
ores  would  have  been  of  much  lower  grade. 

Sheeted  veins. — The  mineralized  sheeted  zones  constitute  the  most 
characteristic  deposits  of  the  district  and  occur  in  practically  all  the 
rocks,  although  particularly  common  in  breccia.  They  consist  of  a 
varying  number  of  narrow,  approximately  parallel  fissures,  together 
composing  a  sheeted  zone  that  may  range  from  a  fraction  of  a  foot  to 
50  or  60  feet  in  width.  Such  uncommonly  wide  zones  of  fissuring, 
however,  can  usually  be  resolved  into  two  or  more  sheeted  zones  lying 
so  close  together  that  the  whole  constitutes  for  practical  purposes  a 
single  ore  body,  as  in  the  Captain  vein  system  of  the  Portland  mine. 
Usually  the  sheeted  zones  are  from  2  to  10  feet  in  width.  In  other 
cases  the  fissures  may  be  very  numerous,  the  rock  for  a  foot  or  more 
in  width  being  divided  into  thin  parallel  slabs,  while  on  each  side  of 
this  medial  portion  the  fissures  become  farther  and  farther  apart  as 
the  lode  grades  into  the  normal  country  rock  of  the  vicinity.  In  still 
other  cases  there  may  be  two  main  fissures,  3  or  4  feet  apart,  accom- 
panied b}^  more  or  less  irregular  fracturing  of  the  intervening  and 
adjacent  rock.  As  a  rule  the  fissures  are  mere  cracks,  showing  no 
brecciation,  slickensiding,  or  other  evidence  of  tangential  movement 
of  the  walls.  Usually  the  tellurides  are  exclusively  confined  to  the 
narrow  fissures  and  cracks,  and  do  not,  in  this  type  of  deposit,  in  any 
sense  constitute  a  replacement  of  the  country  rock.  The  rocks  in  the 
vicinity  of  the  fissures  are  partly  replaced  by  dolomite,  pyrite,  and 
a  little  fluorite;  the  telluride  ores,  however,  do  not  share  this  pro- 
pensity, but  coat  the  open  fissures,  associated  with  a  little  quartz  and 
fluorite.  Replacement  by  tellurides  does  occur  in  two  other  types  of 
deposits,  to  be  described  later;  but  as  regards  the  simple  veins  and 
sheeted  zones,  it  will  be  necessary  to  modify  the  results  of  Penrose  by 
restricting  the  metasomatic  role  of  the  tellurides.  In  the  oxidized 
parts  of  the  veins,  such  as  were  almost  exclusively  available  for  obser- 
vation when  Penrose  visited  the  district,  these  relations  can  seldom  be 
clearly  ascertained,  and  would  easily  lead  one  to  overemphasize  replace- 
ment as  a  feature  of  vein  formation.  The  fissures  are  not,  in  general, 
planes  of  faulting.  Appreciable  movement  has  undoubtedly  occurred 
in  some  instances,  but  the  displacement  probably  rarely  exceeded  1  or 
2  feet. 

Although  found  most  abundantly  in  the  breccia  or  trachytic  phono- 
lite,  sheeted  zones  and  single  fissures  are  often  well  developed  in  the 
granite,  as  in  the  El  Paso,  C.  K.  &  N.,  and  Gold  Coin  mines.  While  in 
some  of  these  lodes  the  ore  minerals  are  as  plainly  confined  to  the  fis- 


24  BESUKVEY    OF    CRIPPLE    CREEK    DISTRICT.  [BULL.  254. 

sures  as  in  the  breccia,  in  other  cases  the  ore  to  some  extent  permeates 
the  granite  alongside  the  fissure,  this  constituting  a  deposit  interme- 
diate in  nature  between  types  1  and  2.  They  also  frequently  follow 
phonolite  dikes,  the  general  tendency  of  these  dikes  to  develop  a  platy 
parting  parallel  to  their  walls  being  particularly  favorable  to  the  produc- 
tion of  a  well-defined  sheeted  zone  when  the  direction  of  fissuring  hap- 
pens to  coincide  with  that  of  the  dike. 

The  metasomatic  alteration  accompanying  these  sheeted  zones  is  sur- 
prisingly slight,  and  consists  of  a  partial  replacement  of  the  breccia, 
phonolite,  trachytic  phonolite,  or  "basalt"  by  dolomite  and  pyrite 
accompanied  by  a  small  amount  of  sericite  and  a  little  secondary  potash 
feldspar.  But  even  in  the  most  altered  rock  the  newly  formed  min- 
erals rarely  form  more  than  a  small  percentage  of  the  rock  mass.  The 
alteration  in  granite  exhibits  a  somewhat  different  phase,  described  in 
a  subsequent  paragraph. 

Not  all  the  sheeted  zones  carry  ore,  nor  is  the  ore  of  a  productive 
sheeted  zone  necessarily  coextensive  with  the  fissuring.  The  ore  occurs 
in  pay  shoots  up  to  2,000  feet  in  length  and  1,000  feet  in  depth,  but 
usually  very  much  smaller  than  is  indicated  by  these  limits.  The 
boundary  between  the  ore  and  the  barren  portions  of  the  lode  can  be 
determined,  as  a  rule,  only  by  assays.  No  single  factor  that  can 
account  for  the  localization  of  the  ore  in  these  pay  shoots  has  been 
discovered.  In  some  mines  the  pay  shoots  occur  where  the  lode  is 
intersected  by  cross  fissures;  in  other  mines  no  such  relation  exists. 
In  some  mines  ore  occurs  where  the  fissures  pass  through  phonolite 
dikes;  in  other  mines  the  lode,  elsewhere  productive,  becomes  barren 
when  it  enters  phonolite;  while  in  still  others  the  presence  of  the 
phonolite  has  had  no  apparent  influence  upon  ore  deposition.  It 
thus  appears  that  the  occurrence  of  two  or  more  favorable  factors  is 
necessary  to  determine  the  position  of  a  pay  shoot  in  a  lode.  The 
discovery  of  these  factors  is  one  of  the  unsolved  problems  connected 
with  the  Cripple  Creek  district. 

Replacement  deposits  in  granite. — The  replacement  deposits  in 
granite  all  occur  in  close  proximity  to  the  contact  with  the  breccia, 
and  are  well  developed  in  the  Elkton  (Thompson),  Ajax,  Independence, 
and  Portland  mines.  Although  these  bodies  of  ore  are  related  to  fis- 
sures and  occur  particularly  where  several  fissures  intersect,  or  where 
they  meet  a  dike,  the  ore  is  not  confined  to  the  actual  fractures.  The 
rock  in  the  vicinity  of  these  fissures  is  often  extensively  altered.  The 
change  from  altered  to  unaltered  rock,  while  never  perfectly  sharp,  is 
often  fairly  abrupt  and  may  take  place  within  a  distance  of  a  few  feet. 
The  most  obvious  characteristic  of  the  metamorphosed  rock  is  a  porous 
texture  and  a  change  of  the  reddish  color  of  the  normal  granite  to 
grayish  or  greenish  tints.  Closer  examination  shows  that,  while  the 
porphyritic  aggregates  of  pink  microcline,  so  prominent  in  the  Pikes 


LINDGREN  AND 

RANSOME. 


]  TYPES    OP    DEPOSITS.  25 


Peak  type  of  granite,  may  remain  unaltered,  the  rest  of  the  rock,  con- 
sisting originally  of  microcline,  oligoclase,  quartz,  and  biotite,  may  be 
completely  recrystallized  as  a  porous,  vuggy  aggregate  of  secondary 
orthoclase(valencianite),  quartz,  fluorite,  pyrite,  calaverite  or  sylvanite, 
and,  in  exceptional  cases,  sphalerite  and  galena.  The  ore  minerals  are 
partly  inclosed  in  the  other  secondary  minerals,  but  occur  most  abun- 
dantty  with  little  projecting  crystals  of  fluorite,  quartz,  and  valencianite 
on  the  walls  of  the  irregular  pores  so  characteristic  of  the  altered  rock. 
The  biotite  of  the  original  granite  yields  most  readity  to  alteration,  and, 
in  rock  otherwise  almost  entirely  unaltered,  may  be  changed  to  an 
aggregate  of  fluorite,  quartz,  and  ore  minerals.  Some  of  the  ore  of 
the  Ajax  mine  exhibits  well  this  initial  stage  of  alteration.  With  fur- 
ther alteration  the  original  quartz  and  oligoclase  of  the  granite  are 
attacked.  The  quartz,  originally  in  large  homogeneous  and  irregular 
grains,  recrystallizes  as  aggregates.  Secondaiy  orthoclase  or  valenci- 
anite forms  often  in  clear,  sharply  idiomorphic  crystals,  which  either 
project  into  open  cavities  or  form  aggregates  with  the  secondary  quartz. 
In  many  cases,  however,  the  secondary  valencianite  results  from  the 
recrystallization  of  the  older  microcline  practically  in  place.  The  two 
generations  are  sometimes  distinguishable  by  the  greater  clearness  and 
more  or  less  idiomorphic  form  of  the  younger  mineral  and  the  absence 
of  the  characteristic  microcline  twinning.  But  it  is  often  impossible 
to  determine  the  line  between  feldspar  which,  from  its  association  with 
quartz  and  fluorite,  is  clearly  secondary  and  the  original  microcline  of 
the  granite.  Occasionally  a  little  calcite  may  be  detected  in  the 
altered  granite,  but  this  is  rare.  The  original  apatite  and  zircon  of 
the  granite  are  not,  so  far  as  observed,  affected  by  the  alteration 
described. 

While  the  replacement  deposits  in  granite  are  important  because  of 
their  size  and  the  readiness  with  which  the  ore  may  be  mined  free 
from  waste,  the  ore  itself  is  usually  of  lower  grade  than  that  formed 
in  the  fissures  of  the  sheeted  zones. 

Mineralized  "basalt"  dikes. — The  ore  bodies  formed  by  the  minerali- 
zation of  basic  dikes  are  in  some  ways  closely  related  to  the  sheeted  zones 
already  described.  Like  the  phonolite  dikes,  the  "basalt"  exhibits 
a  pronounced  tendency  to  split  into  thin  sheets  parallel  with  the  dike 
walls.  Normally,  the  minute  fissures  so  formed  are  filled  with  veinlets 
of  calcite  and  contain  no  ore.  When,  however,  a  zone  of  fissuring 
coincides  with  the  dike  the  latter  may  be  traversed  by  veinlets  of 
quartz  and  fluorite  carrying  sylvanite  or  calaverite,  while  the  body  of 
the  dike  may  be  impregnated  with  pyrite.  Such  ore  differs  from  that 
of  the  usual  sheeted  zones  in  breccia  or  phonolite  in  that  the  tellurides 
are  not  so  clearly  confined  to  the  actual  fissures,  but  appear  to  some 
extent  to  permeate  the  rock  with  the  pyrite.  The  richest  portion  of 
the  ore,  however,  undoubtedly  occurs  in  the  small  veinlets  in  the  diko, 


26  RESURVEY    OF    CRIPPLE    CREEK    DISTRICT.  [BULL. 254. 

and  usually  near  one  or  both  walls  where  the  fissuring  is  best  devel- 
oped. The  occurrence  of  rich  ore  bodies  in  basic  dikes  in  the  Port- 
land (Anna  Lee),  Moose,  Elkton,  Conundrum,  Pinto,  and  other  mines 
has  tended  to  exaggerate  the  importance  of  these  dikes  in  general, 
and  some  have  even  supposed  a  genetic  relation  to  exist  between 
them  and  the  mineralization  of  the  district. a  Such  an  hypothesis, 
however,  loses  sight  of  the  vast  amount  of  profitless  work  that  has 
been  expended  in  the  district  in  driving  on  the  usually  unproduc- 
tive basaltic  dikes,  and  the  very  small  proportion  of  the  known  ore 
bodies  that  can  be  shown  to  have  any  connection  whatever  with  these 
intrusions.  That  the  basaltic  dikes  are  not  always  readily  mineralized 
even  when  accompanied  by  fissuring  is  shown  in  the  interesting  case 
of  the  Strong  mine,  where  the  ore  occurs  as  mineralized  granite  on 
each  side  of  the  dike,  while  the  latter  is  barren. 

DEPTH   OF   OXIDIZED   ZONE. 

At  a  few  points,  as  in  the  Abe  Lincoln  and  El  Paso  mines,  tellurides 
are  found  almost  at  the  surface.  It  is  much  more  common,  however, 
to  find  an  upper  zone,  from  200  to  400  feet  deep,  in  which  free  gold 
prevails  and  which  gradually  changes  to  the  zone  of  pure  telluride 
ores.  As  may  be  expected  from  the  varying  surface  form  and  condi- 
tions of  drainage,  there  is  great  range  in  the  depth  attained  by  oxida- 
tion. Partial  oxidation  extends  in  many  mines  to  a  depth  of  over 
1,000  feet,  especially  along  the  often  more  or  less  open  fissures.  In 
the  Wild  Horse  mine  the  zone  of  complete  oxidation  reaches  a  depth 
of  1,100  feet  and  then  suddenly  ends.  In  the  Isabella  mine  partial 
oxidation  attained  at  least  1,200  feet,  and  the  same  applies  to  the  Gold 
Coin  mine  in  Victor,  although  telluride  ores  prevail  at  that  depth  as 
well  as  in  many  levels  above.  The  question  is  chiefly  one  of  depth  of 
ground  water  and  of  facilities  for  circulation  of  oxygen.  Further 
data  bearing  upon  this  problem  may  be  found  on  page  31. 

RELATIONS   OF   ORE   BODIES   TO   DEPTH. 

It  is  well  known  that  the  payable  ores  in  auriferous  lodes  are  rarely 
equally  distributed  in  the  lode,  but  form  tabular  bodies  of  more  or  less 
regular  outline.  The  projections  of  these  ore  bodies  on  the  plane  of 
the  lode  often  appear  as  elongated  areas  with  greater  vertical  than 
horizontal  extent.  The  ore  bodies  or  shoots  of  Cripple  Creek  show 
great  similarity  to  those  of  other  gold-bearing  veins;  their  limit  in 
depth  is  usually  as  well  defined  as  their  extent  in  a  horizontal  direction. 

Of  sixty  pay  shoots  of  Cripple  Creek  mines  plotted  together  for 

aStevens,  E.  A.,  Basaltic  zones  as  guides  to  ore  deposits  in  the  Cripple  Creek  district:  Trans.  Am. 
Inst.  Min.  Eng.,  vol.  33, 1903,  p.  686. 


L1NKDANsoMEND]        RELATIONS    OF    ORE    BODIES    TO    DEPTH.  27 

purposes  of  comparison,  over  thirty  extended  from  the  surface  to  a 
depth  of  less  than  500  feet.  The  maximum  individual  production  of 
these  is  less  than  $1,000,000.  Near  six  of  these  ore  bodies  further 
exploration  developed  new  shoots  below  the  old  ones,  but  usually  of 
smaller  extent.  In  practically  all  thirty  cases  the  development  work 
hud  been  carried  down  a  few  hundred  feet  below  the  last  ore  of  the 
surface  shoot.  The  form  of  these  smaller  shoots  is  often  equidimen- 
sional;  in  a  few  cases  the  horizontal  extent  is  greater  than  the  verti- 
cal, or  the  shoot  is  wholly  irregular;  in  many  cases  the  shoot  pitches 
steeply  northward  on  the  plane  of  the  vein  and  the  ratio  of  vertical  to 
horizontal  extent  is  2:1  or  3:1. 

In  eight  of  the  sixty  cases  the  shoot  extended  from  the  surface  to  a 
depth  of  1,000  feet,  or  a  little  more,  and  ended.  Further  development 
to  about  1,500  feet  failed  to  find  new  shoots  of  any  importance,  though 
small  pockets  were  often  discovered.  In  six  of  these  eight  cases  the 
ratio  of  vertical  to  horizontal  extent  varies  from  3:1  to  5:1,  and 
the  shoots  usually  pitch  northward  at  angles  of  60°  to  nearly  90°  from 
the  horizontal.  In  the  remaining  two  cases  the  shoots  have  about  the 
same  horizontal  as  vertical  extent.  The  maximum  horizontal  length 
is  1,300  feet,  while  400  is  much  more  common.  In  two  of  the  sixty 
cases  the  pay  shoot  is  1,500  to  2,000  feet  long,  maximum  depths  of 
600  and  1,000  feet  having  been  attained  and  the  bottom  level  being  still 
in  ore.  In  thirteen  of  the  sixty  cases  the  shoot  began  over  200  feet 
below  the  surface;  in  eight  of  these  the  bottom  of  the  shoot  has  been 
reached,  while  in  five  the  lowest  level  is  still  in  ore.  Steeply  dipping, 
irregular  elongated  forms  prevail.  Many  of  this  group  of  thirteen 
represent  veins  parallel  and  close  to  those  on  which  pay  shoots  out- 
cropping at  the  surface  were  found. 

These  statements  will  give  an  idea  of  the  form  of  the  shoots.  Of 
course,  in  the  case  of  shoots  reaching  the  surface,  a  certain  part  has 
probably  been  removed  by  erosion.  Judging  from  the  shoots  which 
distinctly  began  below  the  surface,  the  normal  form  of  the  ore  bodies 
is  elongated,  vertical,  or  pitching  sharply  northward,  the  ratio  of  ver- 
tical to  horizontal  extension  varying  from  li :  1  to  5:1.  Some  of 
these  shoots  are,  however,  of  about  equal  dimensions,  vertically  and 
horizontally,  while  in  a  few  the  horizontal  dimension  is  the  greater. 

Of  the  known  ore  bodies,  as  few  exceed  1,000  feet  in  length,  so 
very  few  exceed  1,000  feet  in  depth  or  extend  more  than  1,000  feet 
from  the  surface.  Speaking  broadly,  explorations  below  that  limit  have 
not  proved  very  satisfactory.  Drawing  the  lines  a  little  closer,  it  may 
be  said  that  in  proportion  to  the  amount  of  exploration  the  upper  700 
or  800  feet  have  yielded  more  than  the  interval  frpm  that  limit  to  the 
lowest  levels  reached — about  1,500  feet.  It  must  not  be  overlooked, 
however,  that  four  or  five  mines  still  have  good  ore  bodies  at  a  depth 


28  RESURVEY    OF    CRIPPLE    CREEK    DISTRICT.  [BULL.  254. 

of  1,200  to  1,400  feet  from  the  surface.  The  developments  of  the 
next  year  or  two  will  probably  give  a  safer  basis  for  generalization. 

Roughly  speaking,  the  above-mentioned  distribution  holds  good  for 
any  elevation  within  the  district.  In  other  words,  the  principal  pro- 
ductive zone  everywhere  occupies  the  space  from  the  surface  down 
to  about  1,000  feet  below  it,  and  its  lower  limit  thus  forms  a  curved 
surface  approximately  parallel  to  the  surface  of  the  ground. 

It  is  probable  that  the  minimum  depth  of  rock  removed  from  the 
district  by  erosion  amounts  to  1,000  feet  in  the  central  part  and  to 
400  or  500  feet  about  the  periphery.  The  shape  and  number  of  the 
ore  bodies  formerly  existing  in  this  eroded  zone  can  be  only  conjec- 
tured. It  is  probable  that  the  veins  were  formed  shortly  after  the 
close  of  igneous  activity,  while  the  volcano  yet  possessed  a  much 
greater  height  than  at  present.  The  absence  of  hot  waters  and  the 
depth  of  oxidation  attained  indicate  that  vein  formation  at  Cripple 
Creek  is  by  no  means  a  recent  phenomenon. 

The  general  features  of  the  vertical  distribution  of  the  known  ore 
bodies  recorded  above  have  of  late  years  received  more  or  less  recog- 
nition, and  there  has  been  a  decided  tendency  to  attribute  them  to  a 
process  of  secondary  enrichment  effected  by  waters  moving  generally 
downward  from  the  surface.  It  has  been  supposed  a  that  such  waters 
have  carried  down  a  part  of  the  auriferous  contents  of  those  portions 
of  the  lodes  now  removed  by  erosion  and  have  enriched  originally  lean 
pyritic  ores  by  the  secondary  deposition  of  gold  and  silver  tellurides 
and  argentiferous  tetrahedrite,  with  associated  gangue  minerals. 

It  is  clear  that  the  hypothesis  in  question  is  suggested  by  the  dis- 
tribution of  known  pay  shoots.  The  question  arises,  How  far  does 
the  distribution  of  known  pay  shoots  represent  the  distribution  of  all 
the  pay  shoots  in  the  district?  In  other  words,  How  far  has  explora- 
tion been  impartial  in  revealing  ore  bodies  near  the  surface  and  at 
depths  greater  than  1,000  feet? 

It  requires  but  little  examination  to  make  clear  the  fact  that  ore 
bodies  within  1,000  feet  of  the  surface  are  far  more  likely  to  be  discov- 
ered than  those  at  greater  depth.  While  shafts  have  been  sunk  for  a 
few  hundred  feet  without  any  indication  of  ore  and  have  ultimately 
been  developed  into  productive  mines,  such  a  procedure  is  considered 
bold  prospecting,  and  few  well-informed  mining  men  would  seriously 
contemplate  sinking  a  shaft  over  1,000  feet  in  depth  solely  on  the 
expectation  of  finding  possible  ore  bodies  below  that  depth.  Most  of 
the  large  mines  in  the  district  have  started  upon  some  indication  of  ore 
near  the  surface  and  have  grown  by  the  subsequent  discovery  of  other 
lodes  and  ore  bodies  in  the  course  of  their  underground  development. 
As  few  individual  ore  bodies  persist  for  more  than  1,000  feet  in  depth,  by 

a  Bancroft,  Geo.  J.,  Eng.  and  Min.  Jour.,  vol.  74,  1902,  pp.  752-753,  and  vol.  75, 1903,  pp.  111-112. 
Finch,  J.  W.,  Proc.  Colorado  Sci.  Soc.,  vol.  7,  1904,  pp.  193-252. 


LINRISfsoMKND]        RELATIONS    OF    ORE    BODIES    TO    DEPTH.  29 

far  the  greater  part  of  the  underground  prospecting  is  at  less  depths, 
there  being  usually  little  inducement  to  go  deeper,  unless,  as  in  the 
case  of  the  Gold  Coin  and  Portland  mines,  lodes  are  discovered  in 
which  the  ore,  beginning  several  hundred  feet  below  the  surface, 
extends  deeper  than  the  pay  shoot  upon  which  the  mine  was  origi- 
nally opened.  Thus  deep  prospecting  is  usually  confined  to  the 
vicinity  of  the  larger  and  more  persistent  pay  shoots  which  have  been 
followed  down  from  near  the  surface.  Underground  water  has  also 
proved  a  most  serious  obstacle  to  deep  prospecting,  few  properties 
being  able  to  develop  below  the  1,000-foot  zone  unless  there  is  abun- 
dant and  high-grade  ore  in  sight. 

It  may  thus  be  concluded,  without  necessarily  advocating  promiscu- 
ous exploration  below  the  1,000-foot  zone,  that  any  ore  bodies  exist- 
ing below  that  depth  are  far  less  likely  to  be  discovered  than  those 
above,  where  from  the  surface  to  depths  of  several  hundred  feet  the 
rocks  of  the  district  are  riddled  with  shafts,  drifts,  crosscuts,  and 
adits.  It  is  exceedingly  difficult,  however,  to  determine,  even  ap- 
proximately, the  relative  importance  of  this  factor  in  the  problem. 
It  is  probably  safe  to  assume  that  th.e  chances  of  discovering  a  given 
ore  body  within  the  1,000-foot  zone  are  at  least  ten  times  those  of  dis- 
covering an  ore  body  below  that  zone,  and  the  ratio  may  be  very  much 
greater.  It  is  probably  true  that  there  was  originally  more  ore  within 
the  1,000-foot  zone  than  there  is  in  a  corresponding  zone  below,  but 
this  disparity  is  not  necessarily  anything  like  so  great  as  is  indicated 
by  the  vertical  distribution  of  known  pay  shoots. 

Another  important  line  of  inquiry  bearing  upon  the  relations  of  the 
ore  bodies  to  depth  is  concerned  with  the  question  of  the  relative  size 
and  abundance  of  the  fissures  near  the  surface  and  at  greater  depth.  It 
has  been  shown  that  all  the  ore  bodies  are  intimately  connected  with 
fissures.  If  such  fissures  are  generally  smaller  and  less  abundant 
below  the  1,000-foot  zone  than  they  are  within  it,  obviously  there  is 
introduced  a  factor  which  diminishes  the  supposed  importance  of  sec- 
ondary enrichment  by  affording  an  anterior  and  physical  explanation 
for  the  decrease  of  ore  with  increase  of  depth. 

Detailed  examination  of  practically  all  the  accessible  mines  in  the 
Cripple  Creek  district  has  led  to  the  conclusion  that  the  fissures,  which 
ordinarily  are  narrow  and  often  appear  as  mere  cracks,  do  become  less 
abundant  and  less  conspicuous  as  greater  depth  is  attained.  No  mine 
exhibits  this  feature  better  than  the  Stratton's  Independence,  in  which 
the  very  complex  systems  of  productive  fissures  on  the  fifth  and  higher 
levels  contrast  most  strikingly  with  the  few,  insignificant,  and  unpro- 
ductive fractures  visible  on  the  fourteenth  level.  In  less  degree  the 
same  feature  is  shown  in  many  others  of  the  deep  mines,  but  the  rule 
is  not  without  some  very  marked  exceptions. 


30  RESURVEY    OF    CRIPPLE    CREEK    DISTRICT.  [BULL.  264. 

The  dependence  of  the  ore  zone  on  the  surface  would  thrn  merely 
express  the  depth  to  which  fissuring  extended  in  a  conical  volcanic 
mountain. 

We  have  thus  two  factors  of  importance  to  account  for  the  scarcity 
of  ore  shoots  below  the  1,000-foot  level — first,  difficulties  of  develop- 
ment and  exploration,  and  second,  the  disappearance  of  fissures  in 
depth.  They  do  not  seem  to  be  sufficient,  however,  and  it  is  believed 
that  a  third  factor,  as  yet  undiscovered,  exists,  and  that  it  is  related  to 
the  chemistry  of  the  actual  ore  deposition. 

In  those  districts  where  so-called  secondary  sulphide  enrichment  is 
known  to  have  taken  place  the  ore  minerals  exhibit  irr  general  an 
orderly  sequence,  both  in  relative  abundance  and  in  kind,  from  those 
characteristic  of  the  most  highly  enriched  ore  near  the  zone  of  oxida- 
tion to  those  constituting  the  original,  lean,  and  unaltered  ore.  The 
secondary  minerals  produced  are  such  as  can  result  from  rearrange- 
ment and  concentration  of  elements  present  in  different  combinations 
in  the  primary  ores.  At  certain  points  within  this  range  of  alteration 
it  is  possible  to  detect  direct  mineralogical  evidence  of  the  change  of 
one  mineral  to  another,  effected  by  solutions  moving  downward  from 
the  zone  of  oxidation.  In  most  cases  the  secondarily  enriched  ores 
bear  a  recognizable  relation  to  the  lower  limit  of  oxidation. 

Careful  study  of  the  Cripple  Creek  ore  deposits  has  failed  to  discover 
that  the  hypothesis  of  secondary  enrichment  is  supported  by  crucial 
evidence  of  the  kind  just  indicated.  The  minerals  are  not  arranged 
in  any  discoverable  definite  sequence,  nor  does  the  present  investiga- 
tion find  much  to  support  the  view  that  the  rich  telluride  ores,  as  a 
rule,  pass  with  increasing  depth  into  low-grade  pyritic  ores.  Fre- 
quently such  ore  as  occurs  below  a  depth  of  1,000  feet  is  precisely  the 
same  in  character  as  ore  found  within  100  feet  of  the  surface.  Tetra- 
hedrite,  which  has  been  regarded  by  some,  without  definite  proof,  as  a 
secondary  mineral,  occurs  sporadically  throughout  the  district  and  at 
all  depths  reached  by  present  workings.  The  richest  ore  does  not 
uniformly  occur  immediately  below  the  oxidized  ore.  There  is,  in 
fact,  little  indication  of  enrichment  in  the  oxidized  zone  such  as  is  so 
often  found  in  gold-quartz  veins  of  the  normal  type.  Frequently  the 
fresh  telluride  ore  is  extremely  j*ich,  and  high-grade  pockets  occur 
impartially  in  oxidized  and  fresh  portions  of  the  veins.  Neither 
would  it  be  correct  to  say  that  there  is  a  gradual  decrease  in  the  value 
of  ore  in  depth.  It  is  quantity,  not  value,  which  decreases. 

While  it  is  certain  that  pyrite,  and  possibly  other  minerals,  has 
formed  at  more  than  one  period  during  the  mineralization  of  the  dis- 
trict, and  while  it  is  equally  clear  that  in  general  the  rich  tellurides 
were  the  last  of  the  ore  minerals  to  be  deposited,  there  is  apparently 
no  evidence  that  any  one  of  these  minerals  has  been  formed  by  enrich- 
ing solutions  at  the  expense  of  primary  minerals.  So  far  as  definite 


]  UNDERGROUND    WATER.  31 

conclusion  is  warranted  in  an  investigation  as  yet  incomplete,  it 
appears  that  the  unoxidized  ore  deposits  of  the  Cripple  Creek  district 
represent  the  product  of  one  general  period  of  mineralization  and  that 
they  have  not  been  appreciably  modified  by  secondary  enrichment 
during  the  subsequent  erosion  of  the  region. 

UNDERGROUND   WATER. 

The  conditions  of  underground  waters  are  interesting  and  somewhat 
unusual.  A  dry  climate  and  a  heavy  percentage  of  run-off  minimize 
the  annual  additions  to  the  underground  supply.  Nevertheless,  the 
ground-water  level  is  not  unusually  deep,  and  large  quantities  of  water 
are  encountered  in  all  the  mines  below  that  level.  The  original  water 
surface  of  the  district  in  the  volcanic  rocks  stood  at  elevations  of  9,400 
to  9,700  feet,  or  100  to  600  feet  below  the  surface  of  the  ground.  At 
first  pumping  was  commenced  by  individual  mines,  but  it  was  soon 
found  that  the  radius  of  drainage  had  unusual  length — that  is,  that  one 
mine  would  drain  others  situated  at  a  distance.  Drainage  tunnels  were 
then  undertaken,  and  the  Chicago  and  Cripple  Creek,  the  Ophelia,  the 
Standard,  and  lately  the  El  Paso  tunnels  were  driven,  each  of  which 
practically  accomplished  the  drainage  of  a  large  part  of  the  district 
almost  down  to  its  own  level,  thus  showing  that  the  ground  water  is 
limited  in  quantity  and  is  more  of  the  nature  of  a  local  reservoir  than 
a  ' '  subterranean  sea. " 

The  plug  of  volcanic  rocks  which  fills  the  throat  of.  the  old  volcano 
is  rudely  circular,  with  a  diameter  of  3  miles.  This  mass  is  extremely 
porous,  and  is,  moreover,  cut  in  many  directions  by  partly  filled  fissures 
and  sheeted  zones,  so  that  water  can  circulate  within  it  with  compara- 
tive freedom  in  several  directions.  It  retains  this  character  down  to 
the  greatest  depth  yet  reached.  On  the  other  hand,  the  surrounding 
granite  is  relatively  impermeable  and  is  less  traversed  by  open  fissures. 
No  doubt  it  contains  ground  water  down  to  a  depth  of  2,000  feet  or 
more,  but  in  very  much  smaller  quantity,  and  the  circulation  of  this 
water  must  be  extremely  slow.  This  is  clearly  shown  by  the  fact  that 
the  water  in  the  breccia  is  not  drained  by  Cripple  Creek  and  Arequa 
Gulch  below  the  level  of  the  points  where  they  leave  the  volcanic  area. 
Thus  the  volcanic  plug  resembles  a  water-soaked  sponge  inserted  in  a 
hole  cut  in  an  impermeable  substance.  The  drainage  of  the  mines  is 
thereby  greatly  facilitated,  as  it  is  not  necessary  to  extend  the  tapping 
tunnels  to  each  mine. 

The  El  Paso  tunnel,  completed  in  the  winter  of  1903-4,  has  an  ele- 
vation of  8,790  feet  at  the  portal.  Within  a  short  time  it  effectually 
drained  not  only  the  Beacon  Hill  mines  but  also  the  Gold  Hill  mines, 
and  its  influence  extended  even  to  the  Last  Dollar  and  the  Elkton 
mines.  But  the  foregoing  statement  in  relation  to  draining  the  dis- 


32  RESURVEY    OF    CRIPPLE    CREEK    DISTRICT.  [BULL. 254. 

trict  must  be  so  modified  as  to  exclude  a  certain  part  on  the  eastern 
side,  comprising  the  mines  about  Independence  on  the  east  side  of  Bull 
Hill  and  those  on  Battle  Mountain  and  in  the  town  of  Victor,  in  which 
the  effect  of  the  El  Paso  tunnel  is  slight.  The  Findley,  Hull  City, 
Vindicator,  and  Golden  Cycle  mines  about  the  town  of  Independence 
seem  to  occupy  a  separate  drainage  basin,  probably  divided  from  the 
main  area  by  masses  of  relatively  impermeable  rock. 

The  Portland,  Stratton's  Independence,  and  the  other  mines  near 
Victor  occupy  another  drainage  basin.  Of  these  the  Gold  Coin  and 
the  Stratton's  Independence  have  shafts  below  the  level  of  the  El  Paso 
tunnel,  and  their  pumps  have  probably  drained  the  surrounding  terri- 
tory to  a  considerable  extent.  The  influence  of  the  drainage  tunnel 
on  the  Portland  mine  is  a  question  upon  which  opinions  differ. 

The  subject  of  the  drainage  of  the  Cripple  Creek  mines  has  been 
actively  studied  in  late  years,  and  valuable  contributions  to  the  subject 
have  been  made  by  Mr.  Victor  G.  Hills  and  others,  who  have  shown 
that  the  water  can  be  tapped,  without  prohibitive  expense,  down  to  an 
elevation  of  7,500  feet,  or  1,300  feet  below  the  El  Paso  tunnel;  for 
this  depth  a  tunnel  3£  miles  long  would  be  needed.  On  account  of  the 
great  porosity  of  the  rocks  it  is  not  probable  that  the  next  thousand 
feet  below,  the  El  Paso  tunnel  level  will  show  any  great  diminution  in 
the  amount  of  water  stored  in  the  rocks. 

SUBTERRANEAN  GASES. 

During  the  earlier  years  of  Cripple  Creek  no  unusual  amount  of 
mine  gases  was  observed,  but,  as  the  shafts  and  workings  deepened, 
several  properties  began  to  experience  much  annoyance  and  even 
serious  interference  with  work,  often  in  spite  of  vigorous  measures 
for  ventilation.  These  gases  appear  to  issue  chiefly  from  the  breccia, 
especially  where  it  is  of  porous  and  loose  texture,  but  they  sometimes 
flow  from  partly  open  vein  fissures  in  such  quantity  that  a  light  held 
up  to  the  fissures  is  immediately  extinguished.  Thus  far  the  mines 
on  Battle  Mountain  and  those  of  the  Golden  Cycle,  Vindicator,  and 
Isabella  groups  have  suffered  no  inconvenience,  but  most  of  the  mines 
west  of  this  line  have  had  more  or  less  trouble  with  this  subtle  and 
insidious  enemy.  At  least  one  mine  has  been  forced  to  close  down 
entirely,  and  several  others  are  often  obliged  to  abandon  work  for 
days.  Sometimes  the  amount  of  gas  issuing  is  small,  and  ordinary 
ventilation  will  carry  it  away;  again  it  may  issue  in  large  volumes 
and  practically  fill  the  mine  for  some  time.  In  other  mines  the  gas 
persistently  hangs  at  certain  places,  forming  barriers  which  can  be 
passed  only  with  difficulty.  The  outflow  of  gas  is  unquestionably 
related  to  barometric  fluctuations,  though  it  is  usually  locally  reported 


]  SUBTERRANEAN    GASES.  33 

to  be  influenced  by  the  direction  of  the  wind.  The  investigations 
concerning  this  subject  are  not  yet  concluded.  It  may  be  said,  how- 
ever, that  a  sudden  lowering  of  the  barometer  seems  to  be  the  most 
important  factor.  Upon  such  a  fall  the  gas  issues  in  great  volumes, 
but  decreases  when  the  barometer  remains  steadily  low  for  several 
days.  The  gas  is  often  very  heavy,  filling  lower  parts  of  drifts  and 
winzes  like  water,  and  cases  are  reported  in  which  it  has  actually  been 
bailed  from  a  shaft.  Its  temperature  is  somewhat  higher  than  that 
prevailing  in  the  mine  under  normal  conditions. 

It  has  practically  no  smell  or  taste,  but  small  quantities  of  it  easily 
produce  effects  of  suffocation.  Miners  working  in  places  where  this 
gas  is  mixed  with  the  air  soon  experience  various  forms  of  physical 
distress,  and  several  fatal  accidents  have  been  caused  by  men  entering 
drifts  and  winzes  filled  with  it. 

The  characteristics  of  the  gas  seemed  to  point  to  carbon  dioxide, 
and  it  is  generally  so  termed.  Preliminary  determinations  of  carbon 
dioxide  by  a  portable  apparatus  yielded  percentages  which  seemed  far 
too  small  in  comparison  with  the  effects  of  the  gas  examined,  and  led 
to  the  belief  that  some  other  substance  was  present.  Samples  were 
then  collected  and  analyzed.  The  analyses  showed  the  gas  to  be  a 
mixture  of  nitrogen  with  about  20  per  cent  carbon  dioxide  and  a  small 
amount  of  oxygen. 

The  occurrence  of  these  exhalations  over  a  large  part  of  the  ore- 
bearing  area  is  of  much  interest.  They  certainly  increase  in  quantity 
with  depth,  and  it  is  to  be  feared  that  in  some  cases  they  may  seriously 
affect  mining  operations.  The  evil  has  proved  very  difficult  to  cope 
with.  Ventilation  alone  has  rarely  proved  efficient,  and  the  only 
practicable  remedial  measures  appear  to  be  cementation  of  drifts  at 
particularly  bad  places  and  working  the  mine  under  air  lock  at  a  pres- 
sure slightly  exceeding  the  normal. 

The  origin  of  these  gases  can  not  reasonably  be  sought  in  any  such 
explanation  as  the  oxidizing  of  sulphides  and  accompanying  absorption 
of  oxygen.  We  believe  that  they  represent  the  last  exhalations  from 
the  throat  of  the  extinct  Cripple  Creek  volcano. 

FUTURE  OF  THE   DISTRICT. 

To  predict  the  future  yield  of  any  mining  district  is  no  easy  task; 
the  conditions  under  which  most  ores  are  deposited  are  as  yet  too 
imperfectty  understood,  and  the  deposits  themselves  are  usually  too 
erratic  in  form  and  distribution,  to  give  certitude  to  such  predictions, 
even  when  these  are  based  upon  a  careful  study  of  the  history  and 
present  condition  of  a  district.  Nevertheless,  it  is  part  of  the  duty  of 
the  geologists  who  have  officially  investigated  the  Cripple  Creek  dis- 
trict to  interpret  to  the  best  of  their  ability  the  bearing  of  ascertained 
Bull.  254—05 3 


34  RESURVEY    OF    CRIPPLE    CREEK    DISTRICT.  [BULL.  254, 

facts  upon  future  mining  development.  For  such  a  forecast  of  the 
future  moderate  probability  is  all  that  can  be  claimed. 

As  has  been  pointed  out  in  the  preceding  pages,  the  largest  known 
ore  bodies  of  the  district  are  apparantly  confined  within  a  zone  which 
extends  from  the  surface  to  a  depth  of  1,000  feet.  In  general,  explo- 
rations below  that  depth  have  been  much  less  satisfactory,  as  regards 
quantity  of  ore,  than  explorations  above.  It  is  certainly  true  that 
some  large  ore  bodies  as  yet  show  no  sign  of  depletion  in  depth,  and 
that  some  good  pay  shoots  have  been  found  at  a  depth  of  1,400  to 
1,500  feet.  On  the  other  hand,  the  number  of  ore  shoots  that  have 
been  exhausted  with  increase  in  depth  is  considerable. 

It  is  probable  that  the  ore  bodies,  known  or  unknown,  occurring 
below  the  1,000-foot  zone  are  neither  so  large  nor  so  abundant  as 
those  nearer  the  surface.  The  discovery  and  exploitation  of  these 
(Jeeper  ore  bodies  is,  moreover,  beset  with  increasing  difficulties,  chief 
among  which  is  the  problem  of  dealing  with  the  underground  water. 
For  these  reasons  it  is  unlikely  that  the  zone  between  the  1,000-foot 
and  2,000-foot  levels  will  yield  as  much  as  the  zone  between  the  sur- 
face and  the  1,000-foot  level,  but  the  possibility  is  not  denied  that 
sorce  strong  fissures  may  carry  payable  ore  to  far  greater  depths  than 
those  jet  attained. 

As  regards  the  zone  above  the  1,000-foot  or  1,500-foot  level,  it  is 
well  to  bear  in  mind  that  it  still  contains  much  ore,  both  as  parts  of 
known  ore  shoots  and  as  yet  undiscovered  ore  bodies.  It  is  certain 
that  many  of  these  undeveloped  ore  bodies  will  be  mined  in  the  near 
future  and  that  this  zone  will  contribute  the  most  important  part  of 
the  production. 

It  is  probable  that  the  production  of  the  district,  while  exhibiting 
fluctuations,  will  on  the  whole  slowly  decline.  New  ore  bodies  will 
undoubtedly  be  discovered  from  time  to  time,  and  individual  mines 
may  be  as  profitable  in  the  future  as  they  have  been  in  the  past,  or 
even  more  profitable.  An  increased  output  may  be  expected  to 
follow  each  successful  step  in  deep  drainage.  But  existing  conditions 
indicate  that  if  the  maximum  production  of  $18,000,000,  in  1900,  is  to 
be  surpassed  the  increase  will  be  due  to  the  ore  bodies  encountered  in 
the  upper  zone. 


INDEX. 


Page. 

Abe  Lincoln  mine,  location  of 16 

Ajax  mine,  depth  of 19 

Anaconda  mine,  production  of 16 

Anchoria-Leland    mine,    production    and 

depth  of 16 

Bancroft,    G.    J.,    on    downward -moving 

waters 28 

Basalt  dikes,  ore  in 25-26 

Battle  Mountain  vein  system,  mines  on —  18 

Beacon  Hill,  mines  on 17 

Breccia,  occurrence  and  character  of  ...  12, 13-14 

Bruce,  J.,  work  of 8 

Bull  Hill,  mines  on 17 

Calaverite,  composition  of 20 

Calcite,  occurrence  of 21 

Carbonate  Hill,  prospects  on 20 

Celestite,  occurrence  of 21 

•Chlorination  process,  use  of 10 

Conundrum  mine,  depth  of 16 

Cripple  Creek  granite,  occurrence  of 13 

Cross,  Whitman,  work  of 7, 11 

Cyanide  process,  use  of 10 

Damon  mine,  location  of 17 

Dikes,  mineralized  basalt,  description  of  ..  25-26 
Doctor-Jack    Pot    mine,    production    and 

depth  of 16 

Dolomite,  occurrence  of 21 

Douglas,  E.  M.,  work  of 7 

El  Paso  shaft,  depth  of 15 

Elkton  mine,  production  and  depth  of 17 

JElkton  shaft,  depth  of 15 

Evans,  R.  T.,  work  of 7 

Feldspar,  occurrence  of 21 

Finch,  J.  W.,  acknowledgments  to 7 

Finch,  J.  W.,  on  downward-moving  waters.  28 

Fissures,  character  of 22 

See  also  Veins: 

Fluorine  mine,  production  of 20 

Fluorite,  occurrence  of 21 

Galena,  occurrence  of 20 

Gangue  minerals,  description  of 21 

Gases,  subterranean,  discussion  of 32-33 

Globe  Hill,  mines  on 16 

Gold,  discovery  of,  date  of 7, 8 

production  of 8-9 

See  also  Ores. 

•Gold  Coin  mine,  production  of is 

Gold  Coin  shaft,  depth  of. 15, 19 

Gold  Hill,  mines  on 16 

<3old  King  mine,  production  of 16 

-Golden  Cycle  mine,  production  of is 


Page. 
Granite,  occurrence  and  character  of ...  11, 12-13 

replacemen  t  deposits  in 24-25 

Graton,  L.  C.,  work  of 8 

Half  Moon  mine,  production  of 16 

Hills,  V.  G.,  work  of 32 

Hull  City  mine,  production  of 18 

Igneous  rocks,  occurrence  and  character  of.  11-14 

Independence  mine,  production  of 19 

Independence  shaft,  depth  of 15 

Isabella  mine,  oxidation  in,  depth  of 26 

production  and  depth  of 18 

Jerry  Johnson  mine,  location  of 17 

Last  Dollar  mine,  production  and  depth  of.       18 

Lillie  mine,  production  of 18 

Lillie  shaft,  depth  of 9, 15, 18 

Map,  topographic,  revision  of 7-8 

Mary  McKinney  mine,  depth  of 16 

Metallurgy  and  mining,  discussion  of 9-10 

Midget  mine,  production  and  depth  of 16 

Mineralized  basalt  dikes,  description  of 25-26 

Minerals,  description  of 20-21 

Mines,  area  including 14 

description  of 15-20 

methods  of  working 9 

Mining  and  metallurgy,  discussion  of 9-10 

Moon-Anchor  mine,  production  of 16 

Moose  mine,  production  of 17 

Rock,  A.  M.,  work  of 8 

Ore  bodies,  relation  of,  to  depth 26-31 

structure  of 22 

types  of 22-26 

Ores,  character  of 20-21 

treatment  of 10 

Oxidized  ores,  occurrence  and  character  of.        21 

Oxidized  zone,  depth  of 26 

Penrose,  R.  A.  F.,  jr.,  work  of 7,14 

Phonolite,  occurrence  of 12 

Pikes  Peak  granite,  occurrence  of 12 

Pinnacle  mine,  location  of 17 

Portland  mine,  production  of 10, 19 

Portland  vein  system,  mines  on * 19 

Poverty  Gulch,  mines  near 16 

Production  of  gold,  table  showing 9 

Productive  area,  extent  of 14 

Pyrite,  occurrence  of 20 

Quartz,  occurrence  of ' 21 

Raven  Hill,  mines  on 17 

Replacement  deposits  in  granite,  descrip- 
tion of 24-25 

Rhodochrosite.  occurrence  of 21 

Roscoelite,  occurrence  of 21 

35 


INDEX. 


Page. 

Shafts,  depth  of 15 

Sheeted  veins,  description  of 23 

Silver,  occurrence  of,  in  ores 21 

production  of 9 

Sphalerite,  occurrence  of 21 

Stevens,  E.  A.,  on  basalt  dikes 26 

Strong  mine,  production  and  depth  of 19 

Structure  of  ore  bodies,  description  of 22 

Sylvanite,  composition  of 20 

Tellurides,  occurrence  of 20 

Topographic  map,  revision  of 7-8 

Topography,  description  of 11 

Tuff  and  breccias,  occurrence  and  character 

of...  12 


Page. 

Underground  development,  extent  of 15 

Underground  water,  discussion  of 31-32 

Veins,  sheeted,  description  of 23 

Victor  mine,  production  and  depth  of 18 

Vindicator  mine,  production  and  depth  of.        18 

Vindicator  vein  system,  mines  of 18 

Volcanic  rocks,  occurrence  and  character  of  11-14 

W.  P.  H.  mine,  location  of 17 

Water,  underground,  discussion  of 31-32 

Wild  Horse  mine,  oxidation  in,  depth  of. . .       26 
production  of IT 


o 


PUBLICATIONS  OF  UNITED  STATES  GEOLOGICAL  SURVEY. 

[Bulletin  No.  254.] 

The  serial  publications  of  the  United  States  Geological  Survey  consist  of  (1)  Annual 
Reports,  (2)  Monographs,  (3)  Professional  Papers,  (4)  "Bulletins,  (5)  Mineral 
Resources,  (6)  Water-Supply  and  Irrigation  Papers,  (7)  Topographic  Atlas  of 
United  States — folios  and  separate  sheets  thereof,  (8)  Geologic  Atlas  of  the  United 
States — folios  thereof.  The  classes  numbered  2,  7,  and  8  are  sold  at  cost  of  publica- 
tion; the  others  are  distributed  free.  A  circular  giving  complete  lists  may  be  had  on 
application. 

The  Professional  Papers,  Bulletins,  and  Water-Supply  Papers  treat  of  a  variety  of 
subjects,  and  the  total  number  issued  is  large.  They  have  therefore  been  classified 
into  the  following  series:  A,  Economic  geojogy;  B,  Descriptive  geology;  C,  System- 
atic geology  and  paleontology;  D,  Petrography  and  mineralogy;  E,  Chemistry  and 
physics;  F,  Geography;  G,  Miscellaneous;  H,  Forestry;  I,  Irrigation;  J,  Water  stor- 
age; K,  Pumping  water;  L,  Quality  of  water;  M,  General  hydrographic  investiga- 
tions; N,  Water  power;  0,  Underground  waters;  P,  Hydrographic  progress  reports. 
This  bulletin  is  the  forty-ninth  in  Series  A  and  the  sixty-first  in  Series  B,  the 
complete  lists  of  which  follow.  (PP= Professional  Paper;  B=Bulletin;  WS= Water- 
Supply  Paper. ) 

SERIES  A,  ECONOMIC  GEOLOGY. 

B  21.  Lignites  of  Great  Sioux  Reservation:    Report  on  region  between  Grand  and  Moreau  rivers, 

Dakota,  by  Bailey  Willis.    1885.    16  pp.,  5  pis.     (Out  of  stock.) 
B  46.  Nature  and  origin  of  deposits  of  phosphate  of  lime,  by  R.  A.  F.  Penrose,  jr.,  with  introduction 

by  N.  S.  Shaler.    1888.    143  pp.     (Out  of  stock.) 
B  65.  Stratigraphy  of  the  bituminous  coal  field  of  Pennsylvania,  Ohio,  and  West  Virginia,  by  I.  C. 

White.    1891.    212  pp.,  11  pis.    (Out  of  stock.) 
B  111.  Geology  of  Big  Stone  Gap  coal  field  of  Virginia  and  Kentucky,  by  M.  R.  Campbell.    1893.    106 

pp.,  6  pis. 

B  132.  The  disseminated  lead  ores  of  southeastern  Missouri,  by  Arthur  Winslow.    1896.    31  pp. 
B  138.  Artesian-well  prospects  in  Atlantic  Coastal  Plain  region,  by  N.  H.  Darton.    1896.    228  pp.,  19 

pis.     (Out  of  stock.) 
B  139.  Geology  of  Castle  Mountain  mining  district,  Montana,  by  W.  H.  Weed  and  L.  V.  Pirsson.    1896. 

164pp.,  17  pis. 

B  143.  Bibliography  of  clays  and  the  ceramic  arts,  by  J.  C.  Branner.    1896.    114  pp. 
B  164.  Reconnaissance  on  the  Rio  Grande  coal  fields  of  Texas,  by  T.  W.  Vaughan,  including  a  report 

on  igneous  rocks  from  the  San  Carlos  coal  field,  by  E.  C.  E.  Lord.    1900.    100  pp.,  11  pis. 
B  178.  El  Paso  tin  deposits,  by  W.  H.  Weed.    1901.    15  pp.,  1  pi. 

B  180.  Occurrence  and  distribution  of  corundum  in  United  States,  by  J.  H.  Pratt.    1901.    98  pp.,  14  pis. 
B  182.  A  report  on  the  economic  geology  of  the  Silverton  quadrangle,  Colorado,  by  F.  L.  Ransome. 

1901.  266  pp.,  16  pis. 

B  184.  Oil  and  gas  fields  of  the  western  interior  and  northern  Texas  Coal  Measures  and  of  the  Upper 
Cretaceous  and  Tertiary  of  the  western  Gulf  coast,  by  G.  I.  Adams.  1901.  64  pp.,  10  pis. 
(Out  of  stock.) 

B  193.  The  geological  relations  and  distribution  of  platinum  and  associated  metals,  by  J.  F.  Kemp. 

1902.  95  pp.,  6  pis.     (Out  of  stock.) 

B  198.  The  Berea  grit  oil  sand  in  the  Cadiz  quadrangle,  Ohio,  by  W.  T.  Griswold.    1902.    43  pp.,  1  pi.' 
PP  1.  Preliminary  report  on  the  Ketchikan  mining  district,  Alaska,  with  an  introductory  sketch  of 

the  geology  of  southeastern  Alaska,  by  Alfred  Hulse  Brooks.    1902.    120  pp.,  2  pis. 
B  200.  Reconnaissance  of  the  borax  deposits  of  Death  Valley  and  Mohave  Desert,  by  M.  R.  Campbell. 

1902.    23  pp.,  1  pi. 

B  202.  Tests  for  gold  and  silver  in  shales  from  western  Kansas,  by  Waldemar  Lindgren.    1902.    21  pp. 
PP  2.  Reconnaissance  of  the  northwestern  portion  of  Seward  Peninsula,  Alaska,  by  A.  J.  Collier. 

1902.    70  pp.,  11  pis. 

I 


II  ADVERTISEMENT. 

PP  10.  Reconnaissance  from  Fort  Hamlin  to  Kotzebue  Sound,  Alaska,  by  way  of  Dall,  Kanuti,  Allen, 

and  Kowak  rivers,  by  W.  C.  Mendenhall.    1902.    68  pp.,  10  pis. 

PP  11.  Clays  of  the  United  States  east  of  the  Mississippi  River,  by  Heinrich  Ries.    1903.    298  pp.,  9  pis. 
PP  12.  Geology  of  the  Globe  copper  district,  Arizona,  by  F.  L.  Ransome.    1903.    168  pp.,  27  pis. 
B  212.  Oil  fields  of  .the  Texas-Louisiana  Gulf  Coastal  Plain,  by  C.  W.  Hayes  and  William  Kennedy. 

1903.    174pp.,  11  pis. 
B  213.  Contributions  to  economic  geology,  1902;  8.  F.  Emmons,  C.  W.  Hayes,  geologists  in  charge. 

1903.  449pp. 

PP  15.  The  mineral  resources  of  the  Mount  Wrangell  district,  Alaska,  by  W.  C.  Mendenhall  and 

F.  C.  Schrader.    1903.    71  pp.,  10  pis. 

B  218.  Coal  resources  of  the  Yukon,  Alaska,  by  A.  J.  Collier.    1903.    71  pp.,  6  pis. 
B  219.  The  ore  deposits  of  Tonopah,  Nevada  (preliminary  report),  by  J.  E.  Spurr.    1903.    31  pp.,  1  pi. 
PP  20.  A  reconnaissance  in  northern  Alaska,  in  1901,  by  F.  C.  Schrader.    1904.    139  pp.,  16  pis. 
PP  21.  Geology  and  ore  deposits  of  the  Bisbee  quadrangle,  Arizona,  by  F.  L.  Ransome.    1904.    168  pp., 

29  pis. 

B  223.  Gypsum  deposits  of  the  United  States,  by  G.  I.  Adams  and  others.    1904.    129  pp.,  21  pis. 
PP  24.  Zinc  and  lead  deposits  of  northern  Arkansas,  by  G.  I.  Adams.    1904.    118  pp.,  27  pis. 
PP  25.  Copper  deposits  of  the  Encampment  district,  Wyoming-Colorado,  by  A.  C.  Spencer.    1904. 

107  pp.,  2  pis. 
B  225.  Contributions  to  economic  geology,  1903;  S.  F.  Emmons,  C.  W.  Hayes,  geologists  in  charge. 

1904.  527  pp.,  1  pi. 

PP  26.  Economic  resources  of  the  northern  Black  Hills,  by  J.  D.  Irving,  with  contributions  by  S.  F. 

Emmons  and  T.  A.  Jaggar,  jr.    1904.    222  pp.,  20  pis. 

PP  27.  A  geological  reconnaissance  across  the  Bitterroot  Range  and  Clearwater  Mountains 'in  Mon- 
tana and  Idaho,  by  Waldemar  Lindgren.    1904.    123  pp.,  15  pis. 
B  229.  Tin  deposits  of  the  York  region,  Alaska,  by  A.  J.  Collier.    1904.    61  pp.,  7  pis. 
B  236.  The  Porcupine  placer  district,  Alaska,  by  C.  W.  Wright.    1904.    35  pp.,  10  pis. 
B  238.  Economic  geology  of  the  lola  quadrangle,  Kansas,  by  G.  I.  Adams,  Erasmus  Haworth,  and 

W.  R.  Crane.    1904.    83  pp.,  11  pis. 

B  243.  Cement  materials  and  industry  of  the  United  States,  by  E.  C.  Eckel.    1905.    —  pp.,  15  pis. 
B  246.  Zinc  and  lead  deposits  of  northwestern  Illinois,  by  H.  Foster  Bain.    1904.    56  pp.,  5  pis. 
B  247.  The  Fairhaven  gold  placers,  Seward  Peninsula,  Alaska,  by  F.  H.  Moffit.     1905.     —  pp.,  14  pis. 
B  249.  Limestones  of  southwestern  Pennsylvania,  by  F.  G.  Clapp.    1905.    —  pp.,  7  pis. 
B  250.  The  petroleum  fields  of  the  Pacific  coast  of  Alaska,  with  an  account  of  the  Bering  River  coal 

deposit,  by  G.  C.  Martin.    1905.    —  pp.,  7  pis. 
B  251.  The  gold  placers  of  the  Fortymile,  Birch  Creek,  and  Fairbanks  regions,  Alaska,  by  L.  M. 

Prindle.    1905.    —pp.,  16  pis. 
°WS  117.  The  lignite  of  North  Dakota  and  its  relation  to  irrigation,  by  F.  A.  Wilder.    1905.    —  pp., 

—  pis. 
PP  36.  The  lead,  zinc,  and  fluorspar  deposits  of  western  Kentucky,  by  E.  O.  Ulrich  and  W.  S.  Tangier 

Smith.    1905.    —  pp.,  —  pis. 
PP  38.  Economic  geology  of  the  Bingham  mining  district  of  Utah,  by  J.  M.  Boutwell,  with  a  chapter 

on  areal  geology,  by  Arthur  Keith,  and  an  introduction  on  general  geology,  by  S.  F.  Emmons. 

1905.    —pp.,  — pis. 
PP  41.  The  geology  of  the  central  Copper  River  region,  Alaska,  by  W.  C.  Mendenhall.     1905.    —  pp., 

-pis. 

B  254.  Report  of  progress  in  the  geological  resurvey  of  the  Cripple  Creek  district,  Colorado,  by  Walde- 
mar Lindgren  and  F.  L.  Ransome.    1904.    36  pp. 

SERIES  B,  DESCRIPTIVE  GEOLOGY. 

B  23.  Observations  on  the  junction  between  the  Eastern  sandstone  and  the  Keweenaw  series  on 

Keweenaw  Point,  Lake  Superior,  by  R.  D.  Irving  and  T.  C.  Chamberlin.     1885.    124pp., 

17  pis. 

B  33.  Notes  on  geology  of  northern  California,  by  J.  S.  Diller.    1886.    23pp.     (Out  of  stock.) 
B  39.  The  upper  beaches  and  deltas  of  Glacial  Lake  Agassiz,  by  Warren  Upham.    1887.    84  pp.,  1  pi. 

(Out  of  stock.)- 
B  40.  Changes  in  river  courses  in  Washington  Territory  due  to  glaciation,  by  Bailey  Willis.    1887. 

10pp.,  4  pis.    (Out  of  stock.) 
B  45.  The  present  condition  of  knowledge  of  the  geology  of  Texas,  by  R.  T.  Hill.    1887.    94  pp.    (Out 

of  stock.) 

B  53.  The  geology  of  Nantucket,  by  N.  S.  Shaler.    1889.    55pp.,  10  pis.    (Out  of  stock.) 
B  57.  A  geological  reconnaissance  in  southwestern  Kansas,  by  Robert  Hay.    1890.    49  pp.,  2  pis. 
B  58.  The  glacial  boundary  in  western  Pennsylvania,  Ohio,  Kentucky,  Indiana,  and  Illinois,  by  G.  F. 

Wright,  with  introduction  by  T.  C.  Chamberlin.    1890.    112  pp.,  8  pis.     (Out  of  stock. ) 
B  67.  The  relations  of  the  traps  of  the  Newark  system  in  the  New  Jersey  region,  by  N.  H.  Darton. 

1890.    82pp.     (Out  of  stock.) 
S  104.  Glaciation  of  the  Yellowstone  Valley  north  of  the  Park,  by  W.  H.  Weed.    1893.    41  pp.,  4  pis. 


ADVERTISEMENT.  Ill 

B  108.  A  geological  reconnaissance  in  central  Washington,  by  I.  C.  Russell.  1893.  108  pp.,  12  pis, 
(Out  of  stock.) 

B  119.  A  geological  reconnaissance  in  northwest  Wyoming,  by  G.  H.  Eldridge.    1894.    72  pp.,  4  pis. 

B  137.  The  geology  of  the  Fort  Riley  Military  Reservation  and  vicinity,  Kansas,  by  Robert  Hay, 
1896.  35  pp.,  8  pis. 

B  144.  The  moraines  of  the  Missouri  Coteau  and  their  attendant  deposits,  by  J.  E.  Todd.  1896.  71 
pp.,  21  pis. 

B  158.  The  moraines  of  southeastern  South  Dakota  and  their  attendant  deposits,  by  J.  E.  Todd. 
1899.  171  pp.,  27  pis. 

B  159.  The  geology  of  eastern  Berkshire  County,  Massachusetts,  by  B.  K.  Emerson.  1899.  139  pp., 
9  pis. 

B  165.  Contributions  to  the  geology  of  Maine,  by  H.  S.  Williams  and  H.  E.  Gregory.  1900  212  pp., 
14  pis. 

WS  70.  Geology  and  water  resources  of  the  Patrick  and  Goshen  Hole  quadrangles  in  eastern  Wyo- 
ming and  western  Nebraska,  by  G.  I.  Adams.  1902.  50  pp.,  11  pis. 

B  199.  Geology  and  water  resources  of  the  Snake  River  Plains  of  Idaho,  by  I.  C.  Russell.  1902.  192 
pp.,  25  pis. 

PP  1.  Preliminary  report  on  the  Ketchikan  mining  district,  Alaska,  with  an  introductory  sketch  of 
the  geology  of  southeastern  Alaska,  by  A.  H.  Brooks.  1902.  120  pp.,  2pls. 

PP  2.  Reconnaissance  of  the  northwestern  portion  of  Seward  Peninsula,  Alaska,  by  A.  J.  Collier. 
1902.  70  pp.,  11  pis. 

PP  3.  Geology  and  petrography  of  Crater  Lake  National  Park,  by  J.  S.  Diller  and  H.  B.  Patton. 
1902.  167pp.,  19  pis. 

PP  10.  Reconnaissance  from  Fort  Hamlin  to  Kotzebue  Sound,  Alaska,  by  way  of  Dall,  Kanuti.  Allen, 
and  Kowak  rivers,  by  W.  C.  Mendenhall.  1902.  68  pp.,  10  pis. 

PP  11.  Clays  of  the  United  States  east  of  the  Mississippi  River,  by  Heinrich  Ries.    1903.    298  pp.,  9  pis. 

PP  12.  Geology  of  the  Globe  copper  district,  Arizona,  by  F.  L.  Ransome.    1903.    168  pp.,  27  pis. 

PP13.  Drainage  modifications  in  southeastern  Ohio  and  adjacent  parts  of  West  Virginia  and  Ken- 
tucky, by  W.  G.  Tight.  1903.  Ill  pp.,  17  pis. 

B  208.  Descriptive  geology  of  Nevada  south  of  the  fortieth  parallel  and  adjacent  portions  of  Cali- 
fornia, by  J.  E.  Spurr.  1903.  229  pp.,  8  pis. 

B  209.  Geology  of  Ascutney  Mountain,  Vermont,  by  R.  A.  Daly.    1903.    122  pp.,  7  pis. 

WS  78.  Preliminary  report  on  artesian  basins  in  southwestern  Idaho  and  southeastern  Oregon,  by 
I.  C.  Russell.  1903.  51  pp.,  2  pis. 

PP  15.  Mineral  resources  of  the  Mount  Wrangell  district,  Alaska,  by  W.  C.  Mendenhall  and  F.  C. 
Schrader.  1903.  71pp.,  10  pis. 

PP17.  Preliminary  report  on  the  geology  and  water  resources  of  Nebraska  west  of  the  one  hundred 
and  third  meridian,  by  N.  H.  Darton.  1903.  69  pp.,  43  pis. 

B  217.  Notes  on  the  geology  of  southwestern  Idaho  and  southeastern  Oregon,  by  I.  C.  Russell.  1903. 
83  pp.,  18  pis. 

B  219.  The  ore  deposits  of  Tonopah,  Nevada  (preliminary  report),  by  J.  E.  Spurr.    1903.    31  pp.,  1  pi. 

PP  20.  A  reconnaissance  in  northern  Alaska  in  1901,  by  F.  C.  Schrader.    1904.    139  pp.,  16  pis. 

PP21.  The  geology  and  ore  deposits  of  the  Bisbee  quadrangle,  Arizona,  by  F.  L.  Ransome.  1904. 
168pp.,  29  pis. 

WS  90.  Geology  and  water  resources  of  part  of  the  lower  James  River  Valley,  South  Dakota,  by  J.  E. 
Todd  and  C.  M.  Hall.  1904.  47  pp.,  23  pis. 

PP25.  The  copper  deposits  of  the  Encampment  district,  Wyoming,  by  A.  C.  Spencer.  1904.  107pp.,2pls. 

PP  26.  Economic  resources  of  northern  Black  Hills,  by  J.  D.  Irving,  with  chapters  by  S.  P.  Emmons. 
and  T.  A.  Jaggar,  jr.  1904.  222  pp.,  20  pis. 

PP  27.  Geological  reconnaissance  across  the  Bitterroot  Range  and  the  Clearwater  Mountains  in  Mon- 
tana and  Idaho,  by  Waldemar  Lindgren.  1904.  122  pp.,  15  pis. 

PP  31.  Preliminary  report  on  the  geology  of  the  Arbuckle  and  Wichita  mountains  in  Indian  Terri- 
tory and  Oklahoma,  by  J.  A.  Taff,  with  an  appendix  on  reported  ore  deposits  in  the  Wichita 
Mountains,  by  H.  F.  Bain.  1904.  97  pp.,  8  pis. 

B  235.  A  geological  reconnaissance  across  the  Cascade  Range  near  the  forty-ninth  parallel,  by  G.  O. 
Smith  and  F.  C.  Calkins.  1904.  103  pp.,  4  pis. 

B  236.  The  Porcupine  placer  district,  Alaska,  by  C.  W.  Wright.    1904.    35  pp.,  10  pis. 

B  237.  Igneous  rocks  of  the  High  wood  Mountains,  Montana,  by  L.  V.  Pirsson.    1904.    208  pp.,  7  pis. 

B  238.  Economic  geology  of  the  lola  quadrangle,  Kansas,  by  G.  I.  Adams,  Erasmus  Haworth,  and 
W.  R.  Crane.  1904.  83  pp.,  11  pis. 

PP  32.  Geology  and  underground  water  resources  of  the  central  Great  Plains,  by  N.  H.  Darton.  1905. 
—  pp.,  72  pis. 

WS  110.  Contributions  to  hydrology  of  eastern  United  States,  1904;  M.  G.  Fuller,  geologist  in  charge. 
1905.  —pp.,  5  pis. 

B  242.  Geology  of  the  Hudson  Valley  between  the  Hoosic  and  the  Kinderhook,  by  T.  Nelson  Dale. 
1904.  63pp.,  3  pis. 

PP  34.  Delavan  lobe  of  the  Lake  Michigan  glacier  of  the  Wisconsin  stage  of  glaciation  and  associated 
phenomena,  by  W.  C.  Alden.  1904.  106  pp.,  15  pis. 


IV  ADVEKTISEMENT. 

PP  35.-Geology  of  the  Perry  basin  in  southeastern  Maine,  by  G.  O.  Smith  and  David  White.    1905. 

—  pp.  ,6  pis. 

B  243.  Cement  materials  and  industry  of  the  United  States,  by  E.  C.  Eckel.    1905.    —  pp.,  15  pis. 

B  246.  Zinc  and  lead  deposits  of  northeastern  Illinois,  by  H.  F.  Bain.    1904.    56  pp.,  5  pis. 

B  247.  The  Fairhaven  gold  placers  of  Seward  Peninsula,  Alaska,  by  F.  H.  Moffit.    1905.    — pp.,  14  pis. 

B  249.  Limestones  of  southwestern  Pennsylvania,  by  F.  G.  Clapp.    1905.    —  pp.,  7  pis. 

B  250.  The  petroleum  fields  of  the  Pacific  coast  of  Alaska,  with  an  account  of  the  Bering  River  coal 

deposit,  by  G.  C.  Martin.    1905.    —  pp.,  7  pis. 
B  251.  The  gold  placers  of  the  Fortymile,  Birch  Creek,  and  Fairbanks  regions,  Alaska,  by  L.  M. 

Prindle.    1905.    —pp.,  16  pis. 
WS  118.  Geology  and  water  resources  of  a  portion  of  east-central  Washington,  by  F.  C.  Calkins.    1905. 

—  pp.,  4  pis. 

B  252.  Preliminary  report  on  the  geology  and  water  resources  of  central  Oregon,  by  I.  C.  Russell. 

1905.    —  pp.,  24  pis. 
PP  36.  The  lead,  zinc,  and  fluorspar  deposits  of  western  Kentucky,  by  E.  O.  Ulrich  and  W.  S.  Tangier 

Smith.    1905.    —pp.,— pis. 
PP  38.  Economic  geology  of  the  Bingham  mining  district  of  Utah,  by  J.  M.  Boutwell,  with  a  chapter 

on  areal  geology,  by  Arthur  Keith,  and  an  introduction  on  general  geology,  by  S.  F.  Emmons. 

1905.    —pp., —pis. 
PP  41.  The  geology  of  the  central  Copper  River  region,  Alaska,  by  W.  C.  Mendenhall.    1905.    —  pp., 

-pis. 
B  254.  Report  of  progress  in  the  geological  resurvey  of  the  Cripple  Creek  district,  Colorado,  by  Wai- 

demar  Lindgren  and  F.  L.  Ransome.    1904.    36  pp. 

Correspondence  should  be  addressed  to 

THE  DIRECTOR, 

UNITED  STATES  GEOLOGICAL  SURVEY, 

WASHINGTON,  D.  0. 
DECEMBER,  1904. 


LIBRARY  CATALOGUE  SLIPS. 

[Mount  each  slip  upon  a  separate  card,  placing  the  subject  at  the  top  of  the 
second  slip.  The  name  of  the  series  should  not  be  repeated  on  the  series 
card,  but  add  the  additional  numbers,  as  received,  to  the  first  entry.] 


Lindgren,  Waldemar,  1860- 

.  .  .  Report  of    progress  in  the  geological  resurvey 
of  the  Cripple  Creek  district,  Colorado;    by  Waldemar 
I      Lindgren  and  Frederick  Leslie  Ransome.     Washing- 
ton, Gov't  print,  off.,  1904. 

36,  iii  p.     23£cm.     (U.  S.  Geological  survey.     Bulletin  no.  254.) 
Subject  series:   A,  Economic  geology,  49;  B,  Descriptive  geology,  61. 

1.  Geology,  Economic — Colorado.     I.  Ransome,  Frederick    Leslie,  1868- 

Lindgren,  Waldemar,  1860- 

.  .  .  Report  of   progress  in  the  geological  resnrvey 
of  the  Cripple  Creek  district,  Colorado;  by  Waldemar 
I      Lindgren  and  Frederick  Leslie  Ransome.     Washing- 
Is      ton,  Gov't  print,  off.,  1904. 

36,  iii  p.     23£cm.     (U.  S.  Geological  survey.     Bulletin  no.  254. ) 
Subject  series:   A,  Economic  geology,  49;  B,  Descriptive  geology,  61. 

1.  Geology,  Economic — Colorado.     I.  Ransome,  Frederick    Leslie,  1868- 

U.  S.      Geological  survey. 
Bulletins. 

|  no.  254.  Lindgren,  W.  Report  of  progress  in  the  geo- 
logical resurvey  of  the  Cripple  Creek  district, 
Colo.;  by  W.  Lindgren  and  F.  L.  Ransome. 
1904. 


U.  S.     Dept.  of  the  Interior. 

see  also 
U.  S.     Geological  survey. 

Bull.  254— 04— —4 


